ASSESSING MIDDLE AND HIGH SCHOOL STUDENTS’ CONCEPTUAL UNDERSTANDING ABOUT PHOTOSYNTHESIS By Katie J. Clegg B.S. University of Maine, 2007 A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Teaching

The Graduate School The University of Maine December, 2011

Advisory Committee: Molly Schauffler, Assistant Professor, Department of Earth Sciences, Advisor Susan McKay, Professor, Department of Physics and Astronomy, Director, Maine Center for Research in STEM Education Mary Rumpho, Professor, Department of Molecular and Biomedical Sciences

ASSESSING MIDDLE AND HIGH SCHOOL STUDENTS’ CONCEPTUAL UNDERSTANDING ABOUT PHOTOSYNTHESIS By Katie J. Clegg B.S. University of Maine, 2007 A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Teaching

The Graduate School The University of Maine December, 2011

Advisory Committee: Molly Schauffler, Assistant Professor, Department of Earth Sciences, Advisor Susan McKay, Professor, Department of Physics and Astronomy, Director, Maine Center for Research in STEM Education Mary Rumpho, Professor, Department of Molecular and Biomedical Sciences

THESIS ACCEPTANCE STATEMENT

On behalf of the Graduate Committee for Katie Clegg, I affirm that this manuscript is the final and accepted thesis. Signatures of all committee members are on file with the Graduate School at the University of Maine, 42 Stodder Hall, Orono, Maine.

Dr. Molly Schauffler, Assistant Professor, Department of Earth Sciences

(Date)

LIBRARY RIGHTS STATEMENT

In presenting this thesis in partial fulfillment of the requirements for an advanced degree at the University of Maine, I agree that the Library shall make it freely available for inspection. I further agree that permission for “fair use” copying of this thesis for scholarly purpose may be granted by the Librarian. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission.

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ASSESSING MIDDLE AND HIGH SCHOOL STUDENTS’ CONCEPTUAL UNDERSTANDING ABOUT PHOTOSYNTHESIS By Katie J. Clegg Thesis Advisor: Dr. Molly Schauffler An Abstract of the Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science in Teaching December, 2011 My study investigated two major research questions regarding photosynthesis education. 1) To what extent do middle and high school students understand the following five major concepts about photosynthesis and cellular respiration before and after instruction: (a) chlorophyll is necessary for photosynthesis, (b) light is the energy source for photosynthesis, (c) carbon dioxide from the atmosphere is the carbon source for plants, (d) plants undergo cellular respiration, and (e) cellular respiration occurs within all cells. 2) Does there appear to be a relationship between how well teachers are able to predict their students’ responses as a class on the post-survey and the class’s normalized gain? To test these research questions, pre- and post-surveys were administered to five middle school and four high school classes in Maine about photosynthesis (n = 335 students; n = 9 teachers). Teachers answered a methods survey regarding the materials they planned to use, what concepts they were planning to cover, and completed a pedagogical content knowledge survey that asked teachers to predict their students’ responses to the post-survey. All surveys were administered between September 2008 and April 2009.

The main finding (Finding 1) from the results of the student surveys was that middle and high school students in my study lacked the conceptual knowledge about photosynthesis that is required by national and state science standards. Finding 1 has two implications: 1) middle and high school students in my study did not learn the concepts that they are expected to understand as outlined in the science standards, and 2) middle school students are not entering high school with an accurate conceptual understanding about photosynthesis. The main finding (Finding 2) from the results of the teacher surveys is that classes with gains in understanding after instruction were more likely to be taught by teachers who had higher PCK scores (matched predictions). This finding was especially evident in the questions that assessed concepts in which students were shown to have deep-rooted misconceptions. Based on these two findings, I propose suggestions for future research and recommendations for the classroom, including a revised photosynthesis concept survey.

ASSESSING MIDDLE AND HIGH SCHOOL STUDENTS’ CONCEPTUAL UNDERSTANDING ABOUT PHOTOSYNTHESIS By Katie J. Clegg Thesis Advisor: Dr. Molly Schauffler An Abstract of the Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science in Teaching December, 2011 My study investigated two major research questions regarding photosynthesis education. 1) To what extent do middle and high school students understand the following five major concepts about photosynthesis and cellular respiration before and after instruction: (a) chlorophyll is necessary for photosynthesis, (b) light is the energy source for photosynthesis, (c) carbon dioxide from the atmosphere is the carbon source for plants, (d) plants undergo cellular respiration, and (e) cellular respiration occurs within all cells. 2) Does there appear to be a relationship between how well teachers are able to predict their students’ responses as a class on the post-survey and the class’s normalized gain? To test these research questions, pre- and post-surveys were administered to five middle school and four high school classes in Maine about photosynthesis (n = 335 students; n = 9 teachers). Teachers answered a methods survey regarding the materials they planned to use, what concepts they were planning to cover, and completed a pedagogical content knowledge survey that asked teachers to predict their students’ responses to the post-survey. All surveys were administered between September 2008 and April 2009.

The main finding (Finding 1) from the results of the student surveys was that middle and high school students in my study lacked the conceptual knowledge about photosynthesis that is required by national and state science standards. Finding 1 has two implications: 1) middle and high school students in my study did not learn the concepts that they are expected to understand as outlined in the science standards, and 2) middle school students are not entering high school with an accurate conceptual understanding about photosynthesis. The main finding (Finding 2) from the results of the teacher surveys is that classes with gains in understanding after instruction were more likely to be taught by teachers who had higher PCK scores (matched predictions). This finding was especially evident in the questions that assessed concepts in which students were shown to have deep-rooted misconceptions. Based on these two findings, I propose suggestions for future research and recommendations for the classroom, including a revised photosynthesis concept survey.

DEDICATION This thesis is dedicated to my family. To my brother, Matthew Clegg, for his unwavering support; my father, Michael Clegg, for always encouraging me to achieve my goals; and my mother, Kathryn Clegg, who has supported me every step of the way. You have all shaped me into the person that I am today and I thank you.

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ACKNOWLEDGEMENTS Thank you to everyone in the M.S.T program for all your help and support. Many thanks go to my advisor, Dr. Molly Schauffler, for her support and advice throughout this project. Thank you to the other members of my committee: Dr. Susan McKay and Dr. Mary Rumpho Kennedy. Their different perspectives and suggestions helped to make my study that much better. A special thank you to Dr. William Halteman for all the guidance he offered on the statistical tests necessary for my study.

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TABLE OF CONTENTS DEDICATION....................................................................................................................iii ACKNOWLEDGEMENTS................................................................................................iv LIST OF TABLES..............................................................................................................xi LIST OF FIGURES..........................................................................................................xvi

Chapter 1.

INTRODUCTION...................................................................................................1 1.1. Expectations for middle and high school students............................................1 1.2. Assessing students’ understanding about photosynthesis.................................2 1.3. Teachers’ pedagogical content knowledge and student learning......................4 1.4. Purpose of my study.........................................................................................5

2.

PHOTOSYNTHESIS.............................................................................................6 2.1. Light reactions and the Calvin cycle.................................................................7 2.2. Chlorophyll pigments........................................................................................9

3.

LITERATURE REVIEW......................................................................................11 3.1. What are middle and high school students expected to know about photosynthesis?..............................................................................................11 3.1.1. Middle school standards..................................................................11 3.1.1.1. National Science Standards: Grades 5-8..........................12 3.1.1.2. Maine Learning Results: Grades 5-8...............................12

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3.1.2. High school standards.....................................................................12 3.1.2.1. National Science Standards: High School........................13 3.1.2.2. Maine Learning Results: High School.............................13 3.1.3. Science standards and informed citizens.........................................13 3.2. What misconceptions do students frequently have about photosynthesis?..............................................................................................15 3.2.1. Misconception 1: Location of photosynthesis within plants...........15 3.2.2. Misconception 2: Energy source for plants.....................................16 3.2.3. Misconception 3: Source of biomass (carbon) in plants.................17 3.2.4. Misconception 4: Cellular respiration in plants..............................19 3.3. What is the correlation between teachers’ pedagogical content knowledge (PCK) and student learning?........................................................20 3.3.1. Teacher experience and PCK..........................................................20 3.3.2. Teachers’ content knowledge and PCK..........................................21 3.3.3. Teachers’ predictions versus actual student performance...............21 3.4. Research literature as a context for my study................................................22 4.

METHODS...........................................................................................................23 4.1. Recruitment of teachers..................................................................................23 4.2. Research Question 1: Development of the student survey............................24 4.2.1. Statistical analysis of student surveys.............................................27 4.3. Identifying teaching methods.........................................................................28

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4.4. Research Question 2: Development of teachers’ pedagogical content Knowledge (PCK) survey..............................................................................28 4.4.1. Analysis of the teachers’ PCK survey............................................29 4.5. Confidentiality................................................................................................29 5.

RESULTS.............................................................................................................30 5.1. Research Question 1: Students’ conceptual understanding about photosynthesis................................................................................................31 5.1.1. Misconception 1: Location of photosynthesis within plants (Questions 1 and 2).........................................................................31 5.1.1.1. Middle school responses to Q1 and Q2...........................32 5.1.1.2. High school responses to Q1 and Q2...............................34 5.1.2. Misconception 2: Energy source for plants (Questions 3-5)..........36 5.1.2.1. Energy source for plants: Question 3...............................36 5.1.2.1.1. Middle school responses to Q3.........................36 5.1.2.1.2. High school responses to Q3.............................37 5.1.2.2. Energy source for plants: Question 4...............................38 5.1.2.2.1. Middle school responses to Q4.........................38 5.1.2.2.2. High school responses to Q4.............................39 5.1.2.3. Energy source for plants: Question 5................................41 5.1.2.3.1. Middle school responses to Q5..........................41 5.1.2.3.2. High school responses to Q5..............................42

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5.1.3. Misconception 3: Source of biomass (carbon) in plants (Questions 6a and 6b).......................................................................43 5.1.3.1. Source of biomass (carbon) in plants: Question 6a..........43 5.1.3.1.1. Middle school responses to Q6a........................44 5.1.3.1.2. High school responses to Q6a............................44 5.1.3.2. Source of biomass (carbon) in plants: Question 6b..........46 5.1.3.2.1 Middle school responses to Q6b.........................46 5.1.3.2.2. High school responses to Q6b............................47 5.1.4. Misconception 4: Cellular respiration in plants (Questions 7 and 8)..........................................................................48 5.1.4.1. Cellular respiration in plants: Question 7.........................48 5.1.4.1.1. Middle school responses to Q7..........................49 5.1.4.1.2. High school responses to Q7.............................50 5.1.4.2. Cellular respiration in plants: Question 8.........................50 5.1.4.2.1. Middle school responses to Q8.........................51 5.1.4.2.2. High school responses to Q8.............................52 5.2. Teacher pre- survey: How is photosynthesis taught?.....................................52 5.2.1. Middle school teachers....................................................................52 5.2.2. High school teachers........................................................................55

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5.3. Research Question 2: Measuring teachers’ pedagogical content knowledge (PCK)...........................................................................................58 5.3.1. Middle school teachers....................................................................58 5.3.2. High school teachers........................................................................59 5.3.3. Teachers’ predictions by question...................................................59 6.

DISCUSSION.......................................................................................................61 6.1. Finding 1: Middle and high school students in my study did not have the conceptual knowledge about photosynthesis required by National and State Standards.........................................................................................61 6.1.1. Misconception 1: Only leaves photosynthesize...............................62 6.1.1.1. Recommendations for teaching all cells that contain chlorophyll photosynthesize.............................................64 6.1.2. Misconception 2: Plants use multiple energy sources....................67 6.1.2.1. Recommendations for teaching light is the only energy source for photosynthesis.....................................70 6.1.3. Misconception 3: Plants obtain biomass through the uptake of soil...............................................................................................71 6.1.3.1. Recommendations for teaching plant biomass come from carbohydrate production during photosynthesis......72 6.1.4. Misconception 4: Cellular respiration only occurs in animals.........73 6.1.4.1. Recommendations for teaching cellular respiration and photosynthesis ...........................................................74 6.1.5. Implications of my study..................................................................75

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6.2. Finding 2: Classes with gains after instruction were more likely to be taught by teachers who had high PCK scores.................................................78 6.2.1. Recommendations for further study assessing the relationship between teachers’ PCK and student understanding..........................79 6.3. Limitations.......................................................................................................80 7.

SUMMARY .........................................................................................................83 7.1. Suggestions for future research ......................................................................84 7.2. Recommendations for the classroom .............................................................85

REFERENCES...................................................................................................................87 APPENDICES...................................................................................................................93 Appendix A: Teacher invitation letter....................................................................93 Appendix B: Student pre- and post-survey............................................................94 Appendix C: Teacher pre-survey...........................................................................96 Appendix D: Teacher post-survey.........................................................................97 Appendix E: Institutional Review Board for the Protection of Human Subjects Protocol..............................................................................98 Appendix F: Non-significant results from the student surveys...........................100 Appendix G: Teachers’ predictions of students’ post-survey responses.............118 Appendix H: Revised student survey for classroom use.....................................129 BIOGRAPHY OF THE AUTHOR................................................................................133

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LIST OF TABLES Table 1.1.

Selected MEA items assessing photosynthesis and respiration in grades 8 and 11...........................................................................................3

Table 4.1.

List of the questions used in the student surveys.....................................26

Table 5.1.

Classes that completed portions of the study...........................................30

Table 5.2.

Q 1 & 2; middle school classes’ normalized gains in responses 1 or 2.........................................................................................................34

Table 5.3.

Q 1 & 2; high school classes’ normalized gains in responses 1 or 2........36

Table 5.4.

Q 3; middle school classes’ normalized gains in the correct answer, “when there is light”..................................................................................37

Table 5.5.

Q 3; high school classes’ normalized gains in the correct response “when there is light”..................................................................................38

Table 5.6.

Q 4; middle school classes’ normalized gains in the correct reasoning....................................................................................................39

Table 5.7.

Q 4; high school basic biology classes’ normalized gains of the correct reasoning......................................................................................40

Table 5.8.

Q 4; high school advanced biology classes’ normalized gains of the correct reasoning......................................................................................40

Table 5.9.

Q 5; middle school classes’ normalized gains in the correct answer, “sun”.........................................................................................................42

Table 5.10.

Q 5; high school basic biology classes’ normalized gains of the correct response, “sun”.............................................................................43

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Table 5.11.

Q 6a; middle school classes’ normalized gains in the correct answer that photosynthesis decreases atmospheric carbon dioxide......................44

Table 5.12.

Q 6a; high school basic biology classes’ normalized gains in the correct answer, “carbon dioxide decreases”..............................................45

Table 5.13.

Q 6b; middle school classes’ normalized gains in the correct reasoning..................................................................................................47

Table 5.14.

Q 6b; high school basic biology classes...................................................48

Table 5.15.

Q 6b; high school advanced biology classes’ normalized gains in the correct reasoning................................................................................48

Table 5.16.

Q 7; middle school classes’ normalized gains in the correct answer, “all of the above”......................................................................................49

Table 5.17.

Q 7; high school classes’ normalized gains in the correct response, “all of the above”......................................................................................50

Table 5.18.

Q 8; middle school classes’ normalized gains in the correct answer, “all body cells”.........................................................................................51

Table 5.19.

Q 8; high school classes’ normalized gain in the correct answer, “all body cells”.........................................................................................52

Table 5.20.

Middle school teachers’ responses to the methods survey......................53

Table 5.21.

High school teachers’ responses to the methods survey..........................56

Table 5.22.

Middle school teachers’ predictions (correct option only)......................59

Table 5.23.

High school teachers’ predictions (correct option only)..........................59

Table 5.24.

Teacher predictions compared to students’ responses.............................60

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Table 6.1.

Middle and high school standards relating to chlorophyll and photosynthesis..........................................................................................63

Table 6.2.

2004 8th grade MEA question compared to Q 1 and Q 2 from the middle school student post-survey............................................................63

Table 6.3.

Middle and high school standards relating to light and photosynthesis...........................................................................................67

Table 6.4.

Comparison of 2002 MEA 8th grade question and Q 5 from the middle school student post-survey about a plant’s energy source........................69

Table 6.5.

2005 8th grade MEA question compared to Q 6a and Q 6b from the middle school student post-survey...........................................................71

Table 6.6.

High school state standards relating to cellular respiration and photosynthesis..........................................................................................73

Table 6.7.

Classes that gained were more likely taught by a teacher with high PCK...........................................................................................................78

Table 6.8.

Q 5 teachers’ predictions compared to their class’s normalized gain......79

Table G.1.

Middle school teacher M01; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......118

Table G.2.

Middle school teacher M03; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......119

Table G.3.

Middle school teacher M04; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......120

Table G.4.

Middle school teacher M05; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......121

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Table G.5.

Middle school teacher M06; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......122

Table G.6.

High school teacher H02; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......123

Table G.7.

High school teacher H04; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......124

Table G.8.

High school teacher H07; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......125

Table G.9.

High school teacher H08; teacher post-survey predictions compared to actual students’ responses on the student post-survey.......126

Table G.10.

Q 1; teachers’ predictions compared to their class’s normalized gains........................................................................................................127

Table G.11.

Q 2; teachers’ predictions compared to their classes’ normalized gains........................................................................................................127

Table G.12.

Q 3; teachers’ predictions compared to their classes’ normalized gains........................................................................................................127

Table G.13.

Q 5; teachers’ predictions compared to their classes’ normalized gains........................................................................................................127

Table G.14.

Q 6a; teachers’ predictions compared to their classes’ normalized gains........................................................................................................128

Table G.15.

Q 7; teachers’ predictions compared to their classes’ normalized gains........................................................................................................128

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Table G.16.

Q 8; teachers’ predictions compared to their classes’ normalized gains........................................................................................................128

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LIST OF FIGURES Figure 2.1.

Photosynthesis occurs within organelles called chloroplasts that are located within the cytoplasm of a plant cell.................................................6

Figure 2.2.

Cross-section of a chloroplast, the location of photosynthesis....................7

Figure 2.3.

The light dependent and light independent (Calvin cycle) reactions...........8

Figure 2.4.

The Calvin cycle.........................................................................................9

Figure 5.1.

Q 1 & 2; middle school class M04 (n = 40).............................................33

Figure 5.2.

Q 1 & 2; middle school class M05 (n = 76).............................................33

Figure 5.3.

Q 1 & 2, middle school class M06 (n = 77).............................................34

Figure 5.4.

Q 1 & 2; high school advanced biology class H02 (n = 10)....................35

Figure 5.5.

Q 1 & 2; high school advanced biology class H07 (n = 25)....................35

Figure 5.6.

Q 3; middle school classes that had p-values < 0.05...............................37

Figure 5.7.

Q 4; middle school classes that had p-values < 0.05...............................39

Figure 5.8.

Q 5; middle school classes that had p-values < 0.05...............................42

Figure 5.9.

Q 5; high school advanced biology class that had a p-value < 0.05........43

Figure 5.10.

Q 6a; middle school class that had a p-value < 0.05................................44

Figure 5.11.

Q 6a; high school classes that had p-values < 0.05..................................45

Figure 5.12.

Q 6b; middle school classes that had p-values < 0.05..............................47

Figure 5.13.

Q 7; middle school class that had a p-value < 0.05.................................49

Figure 5.14.

Q 7; high school class that had a p-value < 0.05......................................50

Figure 5.15.

Q 8; middle school class that had a p-value < 0.05..................................51

Figure 6.1.

Figures from textbook showing basic descriptions of photosynthesis.....65

Figure 6.2.

Carbon cycle.............................................................................................76

Figure F.1.

Q 1 & 2; middle school class M01.........................................................101

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Figure F.2. . Figure F.3.

Q 1 & 2; middle school class M03 (n = 26)...........................................102

Figure F.4.

Q 1 & 2; high school basic biology class H08 (n = 12).........................103

Figure F.5.

Q 1 & 2; high school advanced biology class H08 (n = 7)....................103

Figure F.6.

Q 3; middle school classes M01, M04, and M06..................................104

Figure F.7.

Q 3; high school basic biology classes H04 and H08............................105

Figure F. 8.

Q 3; high school advanced biology classes H02, H07, and H08...........105

Figure F.9.

Q 4; middle school classes M01 and M03.............................................106

Figure F.10.

Q 4; high school basic biology classes H04 and H08............................106

Figure F.11.

Q 4; high school advanced biology classes H02, H07, and H08...........107

Figure F.12.

Q 5; middle school classes M01, M03, and M04..................................108

Figure F.13.

Q 5; high school basic biology classes H04 and H08............................109

Figure F.14.

Q 5; high school advanced biology classes H02 and H08.....................109

Figure F.15.

Q 6a; middle school classes M01, M03, M04, and M05.......................110

Figure F.16.

Q 6a; high school basic biology class H08............................................111

Figure F.17.

Q 6a; high school advanced biology classes H02 and H08...................111

Figure F.18.

Q 6b; middle school classes M01 and M03...........................................112

Figure F.19.

Q 6b; high school basic biology classes H04 and H08..........................112

Figure F.20.

Q 6b; high school advanced biology classes H02, H07, and H08.........113

Figure F.21.

Q 7; middle school classes M01, M03, M05, and M06.........................114

Figure F.22.

Q 7; high school basic biology classes H04 and H08............................115

Figure F.23.

Q 7; high school advanced biology classes H02 and H08.....................115

Figure F.24.

Q 8; middle school classes M01, M03, M04, and M06.........................116

Q 1 & 2; high school basic biology class H04 (n = 18).........................102

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Figure F.25.

Q 8; high school basic biology classes H04 and H08............................117

Figure F.26.

Q 8; high school advanced biology classes H02, H07, and H08...........117

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Chapter 1 INTRODUCTION

Photosynthesis is the base of nearly every food web on earth. Organisms that utilize photosynthesis use light energy to convert water and carbon dioxide into sugar molecules (C6H12O6), which in turn are used to build plant tissue. I review the details of how photosynthesis works in Chapter 2. The concept of photosynthesis is prevalent throughout middle and high school standards at both the state and national level. Photosynthesis is not only a required concept for students, but it is essential to understanding energy transformations and the carbon cycle.

1.1. Expectations for middle and high school students Photosynthesis is a fundamental concept in middle and high school life science curricula. Middle school students are expected to understand what photosynthesis is and its role in the ecosystem, this includes general knowledge of the chemical reaction and the concepts of primary producers and food webs. In high school, students learn the details about how photosynthesis works, including chloroplasts, the light dependent reactions and the light independent reactions known as the Calvin cycle, and the connection between photosynthesis and cellular respiration. Both the National and Maine learning standards pertaining to photosynthesis are reviewed in detail in the next chapter.

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1.2. Assessing students’ understanding about photosynthesis In order to provide a framework for my study, it is important to understand how the state will assess student understanding about photosynthesis. At the time of this study, the Maine Department of Education used the Maine Educational Assessment (MEA) to assess students’ understanding of a variety of science topics, including photosynthesis during grades 8 and 11. The MEA was used to determine if students’ knowledge met educational standards. Three released 8th grade test questions were obtained from 2002, 2004, and 2005, along with two 11th grade test questions from 2003 and 2004 (Table 1.1). Data from additional years were not available. The middle school MEA questions assessed students’ conceptual knowledge, while the high school MEA questions assessed students’ knowledge on the details of photosynthesis. For example, the middle school questions asked how plants use light and air, while the high school questions asked about cellular respiration and the effect photosynthesis has on carbon dioxide in the atmosphere. My study assessed whether or not middle and high school biology students have an accurate conceptual understanding about photosynthesis. There are discrepancies in assessment outcomes of the MEA questions, previous research, and even within my study. For example, the 8th grade students assessed in 2002 demonstrated that they understood the sun is the energy source for photosynthesis (MEA Q 1). Conversely, published research has shown mixed results about whether or not students understand that light is the only energy source for photosynthesis. Some studies showed that students did not understand that light is the only energy source for photosynthesis, while others demonstrated that students understood this concept (Barker and Carr 1989a; Lin and Hu 2003; Marmaroti and Galanopoulou 2006; Ozay and Oztas

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2003; Waheed and Lucas 1992). Why are these discrepancies found between previous research and the Maine Educational Assessments?

Question

Grade

1. Plants get the energy they need to live and grow from: A. Air B. Soil C. Water D. Sunlight (78%) 2. Which function do cells containing chloroplasts perform in an organism? A. Photosynthesis (62%) B. Transpiration C. Condensation D. Diffusion 3. Plants need water and sunlight for photosynthesis. What else is necessary for photosynthesis to occur? A. Air (75%) B. Sulfur (5%) C. Iron (3%) D. Nitrogen (17%) 4. Which would most likely decrease the rate of photosynthesis? A. An increase in the amount of water B. An increase in the amount of light C. A decrease in the amount of carbon dioxide (56%) D. A decrease in the amount of oxygen 5. Cellular respiration occurs in which organisms? A. Only organisms that contain chlorophyll B. Only organisms that do not contain chlorophyll C. Only animals D. All organisms (56%)

Year

8

2002

8

2004

8

2005

11

2003

11

2004

Table 1.1. Selected MEA items assessing photosynthesis and respiration in grades 8 and 11. Bolded answers indicate correct options. The percentages in parentheses indicate the students who chose that answer. Middle school questions assessed conceptual understanding while high school questions tested a more detailed understanding about photosynthesis. My study focused on five concepts: (1) chloroplasts are necessary for photosynthesis, (2) light is the energy source for photosynthesis, (3) plants use carbon dioxide from the atmosphere, (4) plants undergo cellular respiration, and (5) cellular

3

respiration occurs within all cells. Common misconceptions regarding these concepts are reviewed further in Chapter 2. My study compared middle and high school students’ responses on the pre- and post-surveys that assessed these five concepts. Previous studies investigating students’ understanding about photosynthesis have not compared middle and high school students’ responses to questions assessing their conceptual knowledge about photosynthesis. It is possible that high school teachers assume that high school students gain the conceptual knowledge about photosynthesis in middle school. In reality, do students really have this knowledge? 1.3. Teachers’ pedagogical content knowledge and student learning Teachers’ pedagogical content knowledge (PCK), or how well teachers understand their students’ misconceptions and conceptual understanding, has been shown to have an impact on student learning. Previous studies have suggested that higher teacher PCK results in a higher rate of student learning (Bruce and Lawrenz 1991; Clermont et al. 1994; Hope and Townsend 1983; Jong 1992; Lightman and Sadler 1993; Nilsson 2008). Lightman and Sadler (1993) studied astronomy teachers’ predictions of their students’ responses and then compared them to actual student gains. They found that teachers tend to predict double the number of students who will correctly answer a question. Does this apply to life sciences and specifically photosynthesis as well? When teachers’ predictions are compared to how well a class performs, will more accurate predictions correlate with higher student gains in understanding after instruction?

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1.4. Purpose of my study My study investigated two primary research questions: 1. To what extent do middle and high school students understand five major concepts about photosynthesis and cellular respiration before and after instruction: (a) chlorophyll is necessary for photosynthesis, (b) light is the energy source for photosynthesis, (c) carbon dioxide from the atmosphere is the carbon source for plants, (d) plants undergo cellular respiration, and (e) cellular respiration occurs within all cells. 2. Does there appear to be a relationship between how well teachers are able to predict their students’ responses as a class on the post-survey and the class’s normalized gain? Is there a similar positive correlation between teachers’ pedagogical content knowledge (PCK) and student gains in understanding when teaching photosynthesis, as found in physical science?

To test these research questions, surveys were administered to middle and high school students before and after instruction about photosynthesis. Teachers who participated in my study were asked to answer a survey about how they teach photosynthesis, and a second survey asked them to predict their students’ responses on the student post-survey. In the following chapters, I provide a content review of photosynthesis, present a literature review of the research on photosynthesis education, describe the methods used in my study, summarize the results of my study, and discuss the findings and implications of this investigation.

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Chapter 2 PHOTOSYNTHESIS

Organisms that photosynthesize are known as photoautotrophs. They sustain themselves without ingesting other organisms or substances derived from other organisms. Photoautotrophs only need light, carbon dioxide, water, and minerals to photosynthesize. Photosynthesis occurs within chloroplasts, which are organelles located within the cytoplasm of a plant cell (Figure 2.1). The chloroplast contains chlorophyll, a green pigment that facilitates the capture of light energy. Chlorophyll is located within the thylakoid, a membrane bound compartment that is organized in stacks called grana, in order to maximize the surface area that is capturing light (Figure 2.2). While most plants are green, there are some exceptions such as red and brown plants. This is a result of accessory pigments that aid in harvesting different wavelengths of light. I explain this in more detail later in this chapter.

Cell Wall Nucleus Cytoplasm

Central Vacuole

Chloroplasts Figure 2.1. Photosynthesis occurs within organelles called chloroplasts that are located within the cytoplasm of a plant cell.

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Membrane Stroma Grana

Thylakoid Figure 2.2. Cross-section of a chloroplast, the location of photosynthesis. The grana are stacks of thylakoids that contain chlorophyll. The stroma is a fluid that contains enzymes for CO2 fixation. 2.1. Light reactions and the Calvin cycle Photosynthesis is represented by the following chemical equation: 12H2O + 6CO2 + light energy → C6H12O6 + 6O2 + 6H2O While the equation for photosynthesis is summarized in one step, photosynthesis actually requires multiple steps using two complex processes, the light dependent reactions and the Calvin cycle, or light independent reactions (Figure 2.3). The light dependent reactions take place on the thylakoid membrane. Light is absorbed by chlorophyll, triggering the transfer of electrons from water to the acceptor, NADP+, generating NADPH. Light energy is also used to bond phosphorous to ADP within the cell to form ATP, in a process referred to as photophosphorylation, and is represented in the following equation: ADP + H2PO4 + light → ATP The ATP made during the light dependent reactions is used as stored chemical energy that is used during the Calvin cycle, during which carbohydrates are formed.

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H2 O

CO2

Light Light Reactions NADP+ ADP

P

ATP

Calvin Cycle

NADPH

Chloroplast Thylakoid

O2

Stroma

CH2O

Figure 2.3. The light dependent reactions take place on the thylakoid membranes and light independent (Calvin cycle) reactions use light energy to convert CO2 and water into carbohydrates within the stroma. The Calvin cycle takes the carbon in CO2 and forms carbohydrates through a series of reactions in the stroma of the chloroplast (Figure 2.4). The carbon atom from CO2 is added to a five-carbon sugar called ribulose biphosphate (RuBP), becoming a sixcarbon intermediate. The intermediate is then split to form two molecules of phosphoglyceric acid (PGA). The enzyme G3P dehydrogenase uses the ATP and NADPH from the light dependent reactions to reduce a molecule of PGA into phosphoglycericaldehyde (PGAL). Some of the PGAL molecules reform the five-carbon sugar with the help of ATP to begin the cycle again. After several round of the Calvin cycle, two molecules of PGAL leave the cycle to form glucose. The glucose that is produced in the Calvin cycle may then undergo cellular respiration to release energy in the following reaction: C6H12O6 + 6O2 → 6H2O + 6CO2 + Energy (ATP)

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CO2 Step 1: 1 carbon atom from CO2 is added to RuPB RuBP Step 2: 6carbon intermediate is split to form PGA

6-Carbon Intermediate

RuBP

PGA

ADP

ATP

ATP

ADP

PGAL Step 5: ATP is used to reform RuBP.

PGAL

NADPH +

NADP

Glucose Step 4: After several rounds, 2 molecules of PGAL leave the cycle and form glucose.

Step 3: The enzyme G3P dehydrogenase uses ATP and NADPH to reduce PGA into PGAL

Figure 2.4. The Calvin cycle takes the carbon in CO2 and forms carbohydrates through a series of reactions. 2.2. Chlorophyll pigments Photosynthesis begins when light is absorbed by the antenna system located within the chloroplast. The antenna system collects light energy and delivers it to the reaction center complexes where the light reactions take place. The antenna system consists of different pigments that can capture light at different wavelengths efficiently and quickly to begin the electron transfer that drives photosynthesis.

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Visible light is a combination of electromagnetic radiation with wavelengths ranging from 380 nm (blues and violets; high energy) to 750 nm (reds and oranges; low energy). In order to maximize the amount of energy being captured there are different types of chlorophyll pigments, and each pigment has its own absorption spectra (the range of light the pigment absorbs most effectively). The pigment chlorophyll a absorbs red and blue light the best. Chlorophyll a is the only pigment that can participate directly in the light dependent reactions. However, accessory pigments (e.g., chlorophyll b and carotenoids) assist in absorbing light and transfer the energy to a special chlorophyll a molecule that triggers the loss of an electron, the start of the light dependent reactions. Accessory pigments have their own absorption spectra, which can provide an advantage to the organism allowing a wider spectrum of light to be absorbed. Chlorophyll b is an accessory pigment found in land plants and green algae, and it absorbs yellow-green light. Carotenoids absorb shades of blue and green light and protect chlorophyll by absorbing excessive light energy. Other accessory pigments include chlorophyll c, found in some algae, diatoms, and dinoflagellates, fucoxanthin, found in brown algae; and phycoblin, a red pigment found in red algae and cyanobacteri

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Chapter 3 LITERATURE REVIEW

In this Chapter, I present an overview of the literature that is pertinent to my study, including what middle and high school students are required to understand about photosynthesis, what previous research has uncovered about students’ misconceptions regarding photosynthesis, and whether or not there is a correlation between teachers’ pedagogical content knowledge and student learning.

3.1. What are middle and high school students expected to know about photosynthesis?

State and national learning standards describe what students are expected to understand about photosynthesis at each grade level.

3.1.1. Middle school standards Maine students are expected to understand several basic concepts about photosynthesis by the time they finish 8th grade. These concepts from the National Science Standards and the Maine Learning Results are listed and described below (National Committee on Science Education Standards and Assessment 1996; Maine Learning Results 2007).

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3.1.1.1. National Science Standards: Grades 5-8 1. Plants and some microorganisms are producers – they make their own food. 2. For ecosystems, the major source of energy is sunlight. Energy enters ecosystems as producers transfer sunlight into chemical energy via photosynthesis. That energy then passes from organism to organism in food webs. 3.1.1.2. Maine Learning Results: Grades 5-8 3. Compare physical characteristics that differentiate organisms into groups (including organisms that use sunlight to make their own food). 4. Describe how animals and plants’ external and internal structures contribute to the variety of ways organisms are able to find food and reproduce. 5. Describe the source and flow of energy in the major food webs. 6. Describe how matter and energy change from one form to another in living things and in the physical environment. 7. Explain that the total amount of matter in the environment stays the same even as its form and location change.

3.1.2. High school standards The concepts required of high school students build upon the above concepts that they learned in middle school. These standards delve deeper into photosynthesis and are described below.

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3.1.2.1. National Science Standards: High School 8. Plant cells contain chloroplasts, the site of photosynthesis. 9. Plants and many microorganisms use solar energy to combine molecules of carbon dioxide and water into complex, energy rich organic compounds and release oxygen to the environment. 10. Energy flows through ecosystems in one direction, from photosynthetic organisms, to herbivores, to carnivores, and decomposers. 11. The energy for life is primarily derived from the sun. 3.1.2.2. Maine Learning Results: High School 12. Describe the critical role of photosynthesis and how energy and the chemical elements that make up molecules are transformed in ecosystems and obey basic conservation laws. 13. Identify structures that help organisms to stay alive. 14. Describe the similarities and differences in the basic functions of cell membranes and of the specialized parts within cells that allow them to capture and release energy.

3.1.3. Science standards and informed citizens Photosynthesis has a direct impact on climate change because it is an integral part of the global carbon cycle. Plants use carbon dioxide from the atmosphere to produce plant biomass (organic matter). Organic matter can then be buried deep within the earth’s crust, and over millions of years it is converted into fossil fuels. Humans harvest

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fossil fuels to provide energy for cars, power plants, and other industrial processes, which expel carbon dioxide into the atmosphere, and thus completing the carbon cycle. Currently, carbon dioxide is being released back into the atmosphere faster than it is being taken out. Carbon dioxide traps outgoing radiation from earth, resulting less outgoing radiation into space. This warming of the atmosphere is leading to shifts in climate around the world (Solomon et al. 2007). Research shows that the public has limited knowledge about the human impact on climate change from fossil fuel emissions and how photosynthesis affects the amount of carbon dioxide in earth’s atmosphere. This can work against public support for programs that are designed to control the amount of carbon dioxide being released into the atmosphere (Bord et al. 2000; Fortner et al. 2000; Lowe et al. 2006). A comprehensive study by Maibach et al. (2009) found that Americans fall into one of six groups when talking about global climate change: alarmed (18%), concerned (33%), cautious (19%), disengaged (12%), doubtful (11%), and dismissive (7%). Most of the disengaged, doubtful, and dismissive Americans believed that humans have no impact on global climate change, and that humans cannot reduce the amount of carbon dioxide in the atmosphere. These citizens may not support policies designed to reduce the impact that humans have on climate change. The science standards reflect the necessity and importance of every citizen to understand photosynthesis and the vital role photosynthesis plays in removing carbon dioxide from the atmosphere, incorporating it into biomass, and eventually into fossil fuels over the course of millions of years.

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3.2. What misconceptions do students frequently have about photosynthesis? A misconception may be thought of as an incorrect assimilation or misapplication of material that was previously taught. A misconception can also be a theory or explanation derived from a student’s individual experience of life events and their interpretations before formal instruction (Simpson and Arnold 1982). Some misconceptions that students commonly have about photosynthesis include ideas about: (1) where photosynthesis occurs in the plant, (2) where a plant gets its energy for photosynthesis, (3) where a plant gets its carbon, and (4) the relationship between cellular respiration and photosynthesis. Students commonly believe that (1) only the leaves of a plant photosynthesize, whereas any cell that contains chlorophyll will photosynthesize, (2) a plant not only gets its energy for photosynthesis from the sun but it also receives energy from a variety of sources like the soil, water, etc., (3) a plant obtains biomass from the soil, and not through the production of carbohydrates from photosynthesis, and (4) only animals undergo cellular respiration.

3.2.1. Misconception 1: Location of photosynthesis within plants Photosynthesis occurs in chloroplasts that contain chlorophyll. Any cell that contains chlorophyll will photosynthesize. High school students often have the misconception that photosynthesis only occurs in the leaves of a plant (Marmaroti and Galanopoulou 2006). Although this is partially correct, because the majority of photosynthesis occurs in the leaves, it is possible that students do not fully comprehend the role or the location of chloroplasts and chlorophyll. If students understood that any

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cell containing chlorophyll photosynthesizes, they would know that any cell containing chloroplasts and chlorophyll would photosynthesize.

3.2.2. Misconception 2: Energy source for plants Plants absorb sunlight energy and convert it to chemical energy via photosynthesis. Studies have shown that high school students understand that the sun is necessary for photosynthesis, but they may not understand the exact role that sunlight plays. For example, in a study of 88 high school students, Ozay and Oztas (2003) found that when students were asked the free-response question, “How do plants benefit from the sun’s energy?” that only 23.86% of students correctly identified that plants manufacture their own food using the sun’s energy. The most common response was that the sun is a heat source for the plants. Marmaroti and Galanopoulou (2006) studied 290 high school students and found that 80% of students correctly answered a multiple-choice question identifying sunlight as the energy source for photosynthesis. However, the question asked in Marmaroti and Galanopoulou’s study did not require any additional explanation. It is possible that these results conflict with results from other studies because many of the students who chose the correct answer did not have the correct reasoning. In another study of 74 high school students, Waheed and Lucas (1992) used openresponse questions (questions that require an explanation) and found that 80% of students did not correctly explain that the sun is the only energy source for photosynthesis. High school students seemed to understand that while the sun is necessary for photosynthesis, and they can correctly identify this in a multiple-choice item, it is possible that they also

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attributed the energy source for photosynthesis to multiple sources, with the sun being the main energy source for photosynthesis. My study used a combination of open-response and multiple-choice, multiple-response questions to delve deeper into students’ understanding about the energy for photosynthesis. Evidence suggests that many middle and high school students are unsure about how plants use and store energy (Eisen and Stavy 1988; Canal 1999; Lin and Hu 2003; Marmaroti and Galanopoulou 2006). Some high school students think that plants trap energy for an extended period of time, and once it is converted to chemical energy through photosynthesis, it is lost (Marmaroti and Galanopoulou 2006). Similarly, many middle and high school students have the misconception that once energy is consumed by the plant, it is destroyed (Anderson et al. 1990; Carlsson 2002a). These findings suggest that students either do not consider the Law of Conservation of Energy or simply do not understand it. In a study done by Eisen and Stavy (1988), many middle and high school students were able to identify that plants are “producers,” but when they were asked what plants produce and from what, only 64% of students mentioned food production (Stavy et al. 1987; Eisen and Stavy 1988). It is necessary for students to understand that photosynthesis converts sunlight energy to chemical energy. This is the basis of energy supply for most food webs on earth.

3.2.3. Misconception 3: Source of biomass (carbon) in plants Photosynthesis is the process of using sunlight energy to convert carbon dioxide (from the atmosphere) and water, into carbohydrates and oxygen. In this reaction, the

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products (solids and gases) are very different from the reactants (gases), and it is a concept that middle and high school students often have difficulty comprehending (Lin and Hu 2003; Marmaroti and Galanopoulou 2006). This could be attributed to students’ lack of chemistry knowledge because high school students take chemistry after biology, and middle school students do not take chemistry at all. The fact that plants use carbon dioxide (gas) to form biomass (solid) requires students to understand that gas is matter which has mass and takes up space. Students must also consider the Law of Conservation of Mass and Matter in order to understand how the reactants are converted to the products during photosynthesis (Stavy 1990; Bar and Travis 1991; Hesse and Anderson 1992; Driver 1994; Novick and Nussbaum 1995; Wilson et al. 2006). Students tend to confuse how plants feed with how animals feed. Many students believe that plants feed as animals do, by consuming carbon (biomass) from the soil rather than carbon dioxide from the atmosphere (Simpson and Arnold 1982; Bell 1985; Barker and Carr 1989a; Barker and Carr 1989b; Ozay and Oztas 2003; Marmaroti and Galanopoulou 2006). When asked why plants get bigger, many middle and high school students attributed it to the materials they take in rather than the tissue they make from carbon dioxide through photosynthesis (Bell 1985; Leach et al. 1992; Ebert-May et al. 2003; Ozay and Oztas 2003; Marmaroti and Galanopoulou 2006). In a study by Stavy et al. (1987) of middle and high school students, 40% claimed that plants obtain organic material from the soil. In another study by Simpson and Arnold (1982) of 240 high school students, 48% of students thought that plants also got their food from the soil. Barker and Carr (1989a) also found similar results in that 58% of high school students surveyed did not identify photosynthesis as a food-making process.

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3.2.4. Misconception 4: Cellular respiration in plants Cellular respiration is an energy releasing process and its chemical reaction is the reverse of photosynthesis, and plants use both processes. Many middle and high school students either do not believe that plants undergo cellular respiration, or they consider photosynthesis as a form of respiration, explaining that plants “breathe in” carbon dioxide and “exhale” oxygen (Simpson and Arnold 1982; Barrass 1984; Stavy et al. 1987; Eisen and Stavy 1988; Canal 1999). Conversely, students may understand photosynthesis and cellular respiration as separate cellular processes, but are not cognizant as to why cellular respiration is essential to plants (Brown 2009). Photosynthesis and cellular respiration are “opposite” at the biochemical level, but complement each other on a larger scale. If students learn the biochemical details, and ignore how matter and energy flow, students may view the two processes as literally opposite rather than complimentary (Songer and Mintzes 1994; Canal 1999; Wilson 2006; Brown 2009). A study by Simpson and Arnold (1982) found that only 51% of the 52 high school students surveyed were able to identify cellular respiration as an energyreleasing process. Many middle and high school students may regard cellular respiration as synonymous with breathing, and that cellular respiration only occurs in lung-like structures (Stavy et al. 1987; Haslam and Treagust 1987; Anderson et al. 1990; Seymore and Longden 1991; Marmaroti and Galanopoulou 2006). A study by Seymore and Longden (1991) of 77 high school students found that 56% had this misconception, where as 78% of students were unable to correctly identify where in the human body cellular respiration takes place.

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3.3. What is the correlation between teachers’ pedagogical content knowledge (PCK) and student learning?

Shulman (1986) first introduced PCK as a reference to a teacher’s ability to interpret content knowledge and transform it in a way that promotes student learning. Transforming content knowledge for students requires teachers to have not only the ability to draw on knowledge of common learning difficulties, but to identify preconceptions of students (Shulman 1986; Grossman 1990; van Driel et al. 1998; Halim and Meerah 2002). Having the knowledge of students’ conceptions and misconceptions, not only helps teachers to interpret students’ actions and thinking, but it also helps when planning effective lessons (Magnusson et al. 1988; Geddis 1993).

3.3.1. Teacher experience and PCK A study by Clermont et al. (1994) found that experienced teachers possess more PCK and a greater variety of representations and strategies for presenting concepts compared to inexperienced teachers. Experienced teachers were also able to use demonstrations more effectively than novice teachers (Clermont 1994; Nilsson 2008). However, studies by Hope and Townsend (1983) and Jong (1992) showed that experienced teachers who failed to consider their students’ way of thinking often failed to teach effectively, no matter how much experience they possessed.

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3.3.2. Teachers’ content knowledge and PCK Teachers’ content knowledge may also influence PCK. A study by Kapyla et al. (2009) showed that teachers with a weak science background did not understand the content, and as a result, could not determine the most important content to include in their lessons. Similarly, since teachers were not sure about the content themselves, they were not aware of their students’ conceptual difficulties about photosynthesis.

3.3.3. Teachers’ predictions versus actual student performance A teacher’s unawareness about the preconceptions and possible difficulties of their students can result in overly optimistic expectations on the effectiveness of their teaching, and thus student achievement (Lightman and Sadler 1993). A study by Bruce and Lawrenz (1991) compared 50 chemistry teachers’ predictions to the actual mathematical knowledge of 276 high school students. In that study, teachers overestimated the amount of students who would be proficient on a mathematical assessment that was administered at the beginning of a chemistry course by an average of 24%. Over-estimating the mathematical knowledge that their students were bringing into a course could have affected how the course was taught. Lightman and Sadler (1993) also compared teachers’ predictions to student performance. They studied high school astronomy teachers’ predicted gains compared to actual student gains, and found that teachers’ predictions were double the actual student gains in knowledge.

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3.4. Research literature as a context for my study The learning standards served as a starting point for deciding which concepts to target. I developed the student survey to assess the conceptual knowledge about photosynthesis that is required by the state and national science standards. The concepts outlined in this chapter were studied because middle and high school students are expected to understand them. Understanding these concepts does not stop after graduation of high school. The knowledge that carbon moves through biological systems from the atmosphere via photosynthesis is also necessary to make informed decisions about public policy as adults such as those regarding deforestation, controlling carbon dioxide emissions, and the consumption of fossil fuels. The second part of my study compared teachers’ predictions to their students’ responses on the post-survey. The ability to accurately predict student responses can be used an indicator of a teacher’s PCK, which has been linked to higher rates of learning in the classroom. Studies that have measured teachers’ predictions and compared them to actual student performance have shown that teachers tend to over-estimate student performance. The studies about teacher PCK that I have outlined were completed in physical science classrooms. There is little research concerning teachers’ PCK and how it affects student learning in life science (Kapyla 2008). This gap is addressed by measuring students’ conceptual understanding about photosynthesis and comparing it to teachers’ predictions of their students’ responses.

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Chapter 4 METHODS

Beginning in August 2008, middle and high school life science teachers in Maine were invited to participate in my study, researching students’ understanding about photosynthesis and teachers’ pedagogical content knowledge (PCK). Teachers who agreed to participate administered a survey about misconceptions concerning the location of chloroplasts and photosynthesis, the role of light in photosynthesis, the carbon source for photosynthesis, and cellular respiration. The student surveys were distributed before and after photosynthesis instruction. Teachers were asked to complete their own surveys. The teacher methods survey was used to gather information about how they plan to teach photosynthesis. The teacher PCK survey was identical to the student survey, except that teachers were asked to predict their students’ responses. Electronic links to the pre-surveys were sent via e-mail to teachers a few weeks before they began to teach photosynthesis. Once the pre-surveys were taken, the links to the post-surveys were sent. The surveys were administered to middle and high school students between September 2008 and April 2009.

4.1. Recruitment of teachers Approximately one hundred individual e-mails were sent (Appendix A) inviting middle and high school life science teachers to participate in my study. For school districts that were chosen, e-mail invitations were sent to all middle school science teachers and all high school biology teachers in said district. School districts were

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identified from the Maine Department of Education website and the teachers’ e-mail addresses were obtained from school websites. The same e-mail invitation was also sent to the Maine Mathematics and Science Alliance Listserv (http://www.mmsa.org/listinfo.php), which is available to all science teachers in the state of Maine. I received approximately 25 responses from this initial invitation to participate. Nine teachers participated in the entire study, which involved administering the student pre- and post-surveys, as well as completing teacher surveys.

4.2. Research Question 1: Development of the student survey Identical surveys (Appendix B) were given to middle and high school students before and after instruction about photosynthesis. The surveys consisted of eight questions that targeted common misconceptions about photosynthesis and are presented in Table 4.1. Questions 1 and 2 addressed the students’ misconception that photosynthesis only occurs in the leaves of a plant (Marmaroti and Galanopoulou 2006). These questions were used together to determine if students would be able to identify that photosynthesis occurs in any cell that contains chlorophyll. Both of these questions were taken verbatim from Marmaroti and Galanopoulou (2006). The most correct answer is that photosynthesis occurs in the green parts of the plant. Questions 3 to 5 asked students to correctly identify the role that light plays in photosynthesis. This concept is central to photosynthesis, and is present in all middle and high school education standards. Question 3 was not modified from its source,

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Marmaroti and Galanopoulou (2006), and the goal was to determine if students understood that photosynthesis occurs when any light is present, including artificial light. Question 4 was modified from Bishop et al. (1986) and asked students to explain their reasoning. Most students understand that light is necessary for photosynthesis, but their reasoning is often flawed as to why. Students’ responses were coded as: no response (0), incorrect (1), partially correct (2), or correct (3). Question 5 sought to determine if students could identify that the only energy source for photosynthesis is the sun. Instructions were modified from Bishop et al. (1986) by asking the students to “check all that apply,” and adding “all of the above” as an option. Previous research has shown that students often attribute a plant’s energy source to many sources instead of a single source. Adding additional options to the question provided an opportunity to determine the different combinations of energy sources the students would choose, and if these combinations would differ between middle and high school students. I hypothesize that middle school students will attribute a plant’s energy source to a more variety of sources compared to the high school students because of their limited understanding of energy. Question 6 addressed students’ understanding about the source of carbon for photosynthesis by asking students to identify the role that photosynthesis plays in the carbon cycle. This question was created because cycles were emphasized in the Maine Learning Results and it required students to apply their understanding about photosynthesis to a larger system. My hypothesis is that high school students would have a deeper understanding about this concept, and that it would be evident in their reasoning.

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Question

Misconception

Source

Modified

Q1. In which part of the plant does photosynthesis take place? A. Photosynthesis takes place in the roots B. Photosynthesis takes place in the leaves C. Photosynthesis takes place in all green parts of the plant D. Photosynthesis takes place in the whole plant

Photosynthesis only occurs in the leaves of a plant

Marmaroti No and Galanopoul ou (2006)

Q2. Which part of the plant contains chlorophyll? A. Chlorophyll is in the roots B. Chlorophyll is in the leaves C. Chlorophyll is in the green parts of the plant D. Chlorophyll is in the whole plant Q3. When does photosynthesis take place? A. Photosynthesis takes place during the day B. Photosynthesis takes place when there is light C. Photosynthesis takes place continuously D. Photosynthesis takes place at night Q4. Do plants need light to live and grow?____________ Explain your reasoning. Q5. A bean plant needs energy to survive and grow. Where does that energy come from? (Check all that apply) A. Air B. Water C. Sun D. Soil E. Fertilizer F. All of the above Q6. What effect does photosynthesis have on carbon dioxide in the atmosphere? A. Photosynthesis increas es carbon dioxide in the atmosphere B. Photosynthesis decreases carbon dioxide in the atmosphere C. Photosynthesis has no effect on carbon dioxide in the atmosphere Explain your reasoning. Q7. Humans engage in respiration; which other living things engage in respiration? (Check all that apply) A. Snail B. Bacteria C. Rose plant D. Cow E. Mushroom F. All of the above Q8. Where in the human body does respiration take place? (Check all that apply) A. Muscles B. Stomach C. Lungs D. Skin E. Brain F. All body cells

Photosynthesis only occurs in the leaves of a plant

Marmaroti No and Galanopoul ou (2006)

Role of light; photosynthesis only occurs during the day

Marmaroti No and Galanopoul ou (2006)

Role of light; plants get their energy from the soil Role of light; plants get their energy from the soil

Bishop et. Yes al (1986)

Source of carbon in photosynthesis

N/A

Cellular respiration only occurs in animals

Bishop et. Yes al (1986)

Cellular respiration only occurs in lung-like structures

Bishop et. Yes al (1986)

Bishop et. Yes al (1986)

N/A

Table 4.1. List of the questions used in the student surveys; the misconceptions they targeted, sources, and whether or not they were modified from the published question.

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Questions 7 and 8 targeted misconceptions about cellular respiration. These questions were modified from Bishop et al. (1986) by changing the instructions to “check all that apply,” as well as adding “all of the above” as an option. These changes were made to make the directions more clear, and to determine what combinations students would choose at each level. Cellular respiration is often taught along with photosynthesis because plants undergo cellular respiration as well as photosynthesis. However, it is a concept most commonly associated with animals, and was assessed using Question 7. Question 8 assessed the ability of middle and high school students to identify that cellular respiration occurs within all cells, not just lung-like structures. My hypothesis is middle school students will have difficulty identifying that plants undergo cellular respiration and that it occurs at the cellular level, especially because they are not required to learn respiration in detail.

4.2.1. Statistical analysis of student surveys Student surveys were grouped by teacher, because it was assumed that a teacher used the same lessons and methods for all of their classes, with the exception of high school advanced and basic biology classes. High school advanced and basic biology classes were separated to determine if there were any differences between students’ conceptual knowledge about photosynthesis. Student responses were analyzed to measure gains in understanding after instruction. Only responses in which the student completed both the pre- and post-surveys were used. A matrix was created aligning a student’s pre-survey response with his or her post-survey response to each question so that shifts in the student’s answers could be measured.

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For each question, the Stuart-Maxwell test was used to calculate the p-value to determine if the class as a whole answered the question differently on the post-survey compared to the pre-survey (Stuart 1955; Maxwell 1970). For middle school classes, a pvalue of less than 0.05 was used to determine significance. For high school classes, a pvalue of less than 0.10 was used because the number of students in each high school class was much lower than the middle school classes. The normalized gain was also calculated to quantify the difference between the pre- and post-surveys (Hake 2002).

4.3. Identifying teaching methods The teacher methods survey (Appendix C) gathered information about which concepts teachers planned to emphasize in their instruction, concepts their students typically struggle with, and what texts or other materials and activities they use to teach photosynthesis.

4.4. Research Question 2: Development of teachers’ pedagogical content knowledge (PCK) survey

Teachers were asked to predict how their students’ would respond to each question on the post-survey to measure their PCK, or how well teachers understand how their students think (Appendix D). In a study by Lightman and Sadler (1993), teachers were asked to estimate the percentage of their students who would choose the correct answer. In order for teachers to be able to complete the survey quickly and easily, it was decided that instead of asking the teachers predict a percentage, they would chose “few/none,” “some,” or “most” of their students would choose that particular option.

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4.4.1 Analysis of the teachers’ PCK survey The results of the teachers’ PCK survey were compared to his/her students’ postsurvey responses. If the teacher selected “most” for a response, in order to satisfy as a match, the majority of their students must have selected that choice. If the teacher selected “some,” more than 5% of their students must have selected that answer to be a match. If “few/none” was selected, fewer than 5% of their students must have selected that choice to qualify as a match. If the prediction was not a match, it was classified as either an under- or over-prediction.

4.5. Confidentiality To maintain confidentiality according to the Institutional Review Board for the Protection of Human Subjects protocol, individual names were removed from all surveys. Responses were coded based on teacher and class period (Appendix E). For example, a high school teacher was given a code of “H,” and a number, “H01,” while a middle school teacher was given the code of “M,” and a number, “M01.” For purposes of matching students’ pre- and post-survey responses, students’ responses were coded and names were then removed from the data. Students were given a code based on their teacher and class period, teacher_class_student number. For example, a student in teacher H01’s period three class, would have a code, “H01_03_01”.

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Chapter 5 RESULTS

A total of 21 middle and high school life science teachers volunteered their classes to participate in my study. Nine teachers completed the entire study (Table 5.1). Only the classes that completed the entire study were analyzed. Middle school teachers with multiple classes were analyzed together, while high school teachers with multiple classes were grouped based on whether or not it was a basic or an advanced biology class. If the basic and advanced biology classes did not differ significantly, the classes were grouped together. This chapter presents the results of significant changes from each question, grouped as a middle school class, a high school basic biology class, or a high school advanced biology class. Non-significant results can be found in Appendix F. Class M01 M02 M03 M04 M05 M06 M07 M08 H01 H02 H03 H04 H05 H07 H08 H09

Student PreSurvey X X X X X X

X X X X X X

Teacher PreSurvey X X X X X X X X X X X X X X X X

Student PostSurvey X

Teacher PostSurvey X

X X X X

X X X X

X

X

X

X X X X X

X X X

Table 5.1. Classes that completed portions of the study, shaded classes completed the entire study.

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5.1. Research Question 1: Students’ conceptual understanding about photosynthesis Student surveys were grouped by class and analyzed using the Stuart-Maxwell test to determine if students answered their post-survey differently than their pre-survey. This test uses a matrix of student responses on the pre- and post-surveys, and ultimately, measures how much the post-survey responses deviate from the pre-survey responses. In addition, the normalized gain () was calculated to determine if there was a loss, no change, or a gain in the correct answer following instruction. Normalized Gain = (% correct on post-survey - % correct on pre-survey) (100 - % correct on pre-survey)

5.1.1. Misconception 1: Location of photosynthesis within plants (Questions 1 and 2)

The misconception that photosynthesis only occurs in the leaves was targeted using Questions 1 and 2 on the student survey. 1. Where in the plant does photosynthesis take place? a. b. c. d.

Photosynthesis takes place in the roots Photosynthesis takes place in the leaves Photosynthesis takes place in all green parts of the plant Photosynthesis takes place in the whole plant

2. Where in the plant are chloroplasts located? a. b. c. d.

Chlorophyll is in the roots Chlorophyll is in the leaves Chlorophyll is in the green parts of the plant Chlorophyll is in the whole plant

After reflecting, I realized that it is possible that Questions 1 and 2 could have been confusing because in some plants, photosynthesis does only occur in the leaves. Further, the option “leaves” is not incorrect because photosynthesis does occur in the

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leaves, and the leaves also contain chlorophyll. However, the most accurate response in both questions is “all green parts”. I used these two questions to determine if the students were able to reason that chlorophyll is necessary for photosynthesis. During this analysis, I created a hierarchy of students’ combined responses to the two questions (Q1/Q2): green parts/green parts (1), leaves/leaves (2), whole plant/whole plants (3), leaves/green parts and green parts/leaves (4), and other combination (5). The responses, “green parts/green parts” and “leaves/leaves,” indicate students likely understand the connection between chlorophyll and photosynthesis. The response, “whole plant/whole plant,” suggests that the student most likely does not understand where photosynthesis takes place, but does understand that chlorophyll is necessary for photosynthesis. Any other combination of responses suggests a poor understanding about where photosynthesis takes place as well as the fact, that chlorophyll is needed for photosynthesis.

5.1.1.1. Middle school responses to Q1 and Q2 Classes M04, M05, and M06 answered the post-survey differently than the presurvey at a 95% significance level (Figure 5.1 to Figure 5.3). These classes exhibited gains in the two best responses in the hierarchy ranging from 0.20 to 0.41 (Table 5.2). The thickness of the arrows represents the number of students moving between responses. The thicker the arrow, the more students moved in that direction. Results from middle school classes M01 and M03 were not significant and are located in Appendix F.

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Pre-Survey (Q1/Q2)

CLASS M04

Post-Survey (Q1/Q2)

(1)

Green parts/Green parts

Green parts/Green parts

(2)

Leaves/Leaves

Leaves/Leaves (15)

Whole plant/Whole plant Other combination

Whole plant/Whole plant Other combination

(22)

Figure 5.1. Q 1 & 2; middle school class M04. The number of students is represented by the thickness of the line (n = 40). Most of the students who answered this question at the bottom of the hierarchy answered higher on the hierarchy on the post-survey. Pre-Survey (Q1/Q2)

CLASS M05 (4)

Green parts/Green parts (6)

Leaves/Leaves

Post-Survey (Q1/Q2) Green parts/Green parts

(1)

(15)

Leaves/Leaves

(1) (6) (1)

Whole plant/Whole plant

Other combination

(1)

(1)

Whole plant/Whole plant

Other combination

(40)

Figure 5.2. Q 1 & 2; middle school class M05 (n = 76). Most of the students answered higher on the hierarchy on the post-survey.

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Pre-Survey (Q1/Q2) Green parts/Green parts

CLASS M06 (1)

Green parts/Green parts

(1) (2)

(6) (1)

Leaves/Leaves (5)

Whole plant/Whole plant

Post-Survey (Q1/Q2)

Leaves/Leaves

(9) (2)

(2)

Whole plant/Whole plant

(2) (2)

Other combination

(44)

Other combination

Figure 5.3. Q 1 & 2, middle school class M06 (n = 77). Many students answered higher on the hierarchy. Some students answered lower on the hierarchy on the post-survey. Class M01 M03 M04 M05 M06

Pre-Survey Responses 1 or 2 16% 8% 8% 15% 16%

Post-Survey Responses 1 or 2 28% 35% 46% 35% 30%

Normalized Gain Responses 1 or 2 0.14 0.29 0.41 0.24 0.20

Table 5.2. Q 1 & 2; middle school classes’ normalized gains in responses 1 or 2. Shaded classes had p-values < 0.05.

5.1.1.2. High school responses to Q 1 and Q 2 There were no statistical differences between the high school advanced biology and basic biology classes on Questions 1 and 2 and will be analyzed as a group. High school classes H02 and H07 answered the post-survey significantly different (p-value < 0.10) than the pre-survey (Figure 5.4 and Figure 5.5). Both classes gained in knowledge

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after instruction (Table 5.3). The results from high school classes H04 and H08 were not significant and are located in Appendix F.

Pre-Survey (Q1/Q2)

CLASS H02

Post-Survey (Q1/Q2)

Green parts/Green parts

Green parts/Green parts (1)

Leaves/Leaves

Leaves/Leaves

(1)

Whole plant/Whole plant

Whole plant/Whole plant (5)

Other combination

Other combination

(3)

Figure 5.4. Q 1 & 2; high school advanced biology class H02 (n = 10). Most students moved higher in the hierarchy after instruction.

Pre-Survey (Q1/Q2) Green parts/Green parts

CLASS H07 (4)

Post-Survey (Q1/Q2) (1)

(4)

Leaves/Leaves (1)

Green parts/Green parts

Leaves/Leaves

(1)

Whole plant/Whole plant

Whole plant/Whole plant (7)

Other combination

Other combination

(7)

Figure 5.5. Q 1 & 2; high school advanced biology class H07 (n = 25). Most students moved higher in the post-survey.

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Class H02

Pre-Survey Responses 1 or 2 20%

Post-Survey Responses 1 or 2 70%

Normalized Gain Responses 1 or 2 0.63

H04 H07 H08

28% 40% 0%

39% 62% 14%

0.15 0.37 0.14

Table 5.3. Q 1 & 2; high school classes’ normalized gains in responses 1 or 2. Shaded classes had p-values < 0.10. All classes gained in the two best answers after instruction.

5.1.2. Misconception 2: Energy source for plants (Questions 3-5) Many students seemed to have had misconceptions or misunderstood the role that light plays in photosynthesis, as discussed in Chapter 2. Questions 3 to 5 measures what students understood about the role of light in photosynthesis. 5.1.2.1. Energy source for plants: Question 3 Q 3. When does photosynthesis take place? A. B. C. D.

Photosynthesis takes place during the day Photosynthesis takes place when there is light* Photosynthesis takes place continuously Photosynthesis takes place at night

This question sought to determine if students would connect light to photosynthesis. The correct answer is, “photosynthesis occurs when there is light;” however two common incorrect responses were “during the day” and “continuously.” 5.1.2.1.1. Middle school responses to Q 3 Middle school classes M03 and M05 are the only classes that answered the postsurvey significantly differently than the pre-survey (Figure 5.6). Both classes’ knowledge of the correct answer decreased after instruction (Table 5.4). Classes M03

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and M05 had large numbers of students who chose the incorrect response, “during the day,” on the post-survey.

Class M03 = -0.17

n = 27

Class M05 = -0.16

n = 75

Figure 5.6. Q 3; middle school classes M03 and M05 had p-values < 0.05. Normalized gain (), number of students (n), pre-survey (black bars), and post-survey (grey bars). These classes lost in the correct response (*) and increased in the incorrect response, “during the day.” Class M01 M03 M04 M05 M06

Pre-Survey “When there is light” 53% 56% 54% 57% 64%

Post-Survey “When there is light” 66% 48% 49% 51% 61%

Normalized Gain “When there is light” 0.29 -0.17 -0.10 -0.16 -0.10

Table 5.4. Q 3; middle school classes’ normalized gains in the correct answer, “when there is light”. Shaded classes M03 and M04 had p-values < 0.05.

5.1.2.1.2. High school responses to Q 3 No significant differences were found between the advanced and basic biology classes and thus, were grouped together. None of the high school classes answered the pre- and post-surveys significantly differently. Three classes had negative normalized gains, while one class had a positive normalized gain (Table 5.5).

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Class H02 H04 H07 H08

Pre-Survey “When there is light” 70% 83% 68% 63%

Post-Survey “When there is light” 50% 56% 72% 42%

Normalized Gain “When there is light” -0.70 -1.70 0.13 -0.57

Table 5.5. Q 3; high school classes’ normalized gains in the correct response “when there is light”. No classes changed significantly after instruction.

5.1.2.2. Energy source for plants: Question 4 Q 4. Do plants need light to live and grow? Explain your reasoning.

Question 4 asked students to identify that light is necessary for photosynthesis, and then to explain their reasoning. Explanations fell into one of four categories: no response, incorrect, partially correct, or correct. A no response answer was either left blank or the student answered some form of “I don’t know.” An incorrect response contained incorrect reasoning; for example, “light is a plant’s heat source”. Partially correct was a response without any elaboration; for example, “to grow”. A correct response must have included reasoning that mentioned light as the energy source for photosynthesis.

5.1.2.2.1. Middle school responses to Q 4 Middle school classes M04, M05, and M06 answered Question 4 differently on the post-survey than on the pre-survey at a 95% significance level (Figure 5.7). All three of these classes gained after instruction (Table 5.6).

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Class M04 = 0.38

n = 40

Class M05 = 0.54

n = 75

Class M06 = 0.70

n = 72

Figure 5.7. Q 4; middle school classes that had p-values < 0.05. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars).

Class M01

Pre-Survey “When there is light” 41%

Post-Survey “When there is light” 54%

Normalized Gain “When there is light” 0.22

M03

56%

63%

0.17

M04

22%

51%

0.38

M05

63%

83%

0.54

M06

39%

82%

0.70

Table 5.6. Q 4; middle school classes’ normalized gains in the correct reasoning. Shaded classes had p-values < 0.05.

5.1.2.2.2. High school responses to Q 4 The post-survey responses between the advanced and basic biology classes were significantly different and will be discussed separately.

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Basic biology classes: Neither of the basic biology classes answered the pre- and post-surveys differently at a 90% significance level. Normalized gains varied; class H08 had a gain of -0.33 and class H04 showed a gain of 0.08 (Table 5.7).

Class

Pre-Survey

Post-Survey

Normalized Gain

Basic H08

75%

67%

-0.33

Basic H04

28%

33%

0.08

Table 5.7. Q 4; high school basic biology classes’ normalized gains of the correct reasoning. Neither class’s changes were significant. Advanced biology classes: None of the advanced biology classes answered the post-survey differently than the pre-survey. All of the advanced biology classes had positive normalized gains varying from 0 to 1.00 (Table 5.8). Advanced biology students exhibited a high rate of the correct reasoning on both the pre- and post-surveys.

Class

Pre-Survey

Post-Survey

Normalized Gain

Advanced H02 Advanced H07 Advanced H08

90%

90%

0

84%

92%

0.50

86%

100%

1.00

Table 5.8. Q 4; high school advanced biology classes’ normalized gains of the correct reasoning. None of the classes’ changes were significant.

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5.1.2.3. Energy source for plants: Question 5 Q 5. A bean plant needs energy to survive and grow. Where does that energy come from? (Check all that apply) A. Air B. Water C. Sun* D. Soil E. Fertilizer F. All of the above

Question 5 asked students to correctly identify that the only energy source for plants is the sun. Students were given the option to choose a combination of choices because of the common misconception that plants receive energy from a combination of sources.

5.1.2.3.1. Middle school responses to Q 5 Middle school classes M05 and M06 answered the pre- and post-surveys differently at a 95% significance level (Figure 5.8). Class M05 showed gains while class M06 lost in the correct answer, “sun,” after instruction (Table 5.9). Class M06 had the largest gain in the correct answer with a normalized gain of 0.16 while class M05 had a large change in students who picked the combination air, water, and sun (the reactants for photosynthesis), from 3% in the pre-survey to 40% in the post-survey. The most popular answer in all of the classes was “all of the above” in both surveys.

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Class M05 n = 75 = -0.11

Class M06 n = 77 = 0.16

Figure 5.8. Q 5; middle school classes M05 and M06 with p-values < 0.05. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars). Class M05 lost in the correct response (*) while class M06 gained after instruction. Class M01 M03 M04 M05 M06

Pre-Survey “Sun” 9% 26% 7% 16% 5%

Post-Survey “Sun” 10% 19% 5% 7% 21%

Normalized Gain “Sun” 0.02 -0.01 -0.03 -0.11 0.16

Table 5.9. Q 5; middle school classes’ normalized gains in the correct answer, “sun”. Classes M05 and M06 (shaded) had significant changes after instruction.

5.1.2.3.2. High school responses to Q 5 No significant differences were found between the advanced and basic biology classes and they were grouped together by teacher. Class H07 answered the pre- and post-survey differently at a 90% significance level, and was the only class to gain in the correct answer, “sun,” after instruction (Figure 5.9; Table 5.10). In all other classes, the most popular response was, “all of the above.”

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Class H07 n = 25 = 0.58

Figure 5.9. Q 5; high school advanced biology class H07 had p-value < 0.10. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars). Class H07 gained in the correct response (*) after instruction. Class H02 H04 H07 H08

Pre-Survey “Sun” 10% 11% 4% 11%

Post-Survey “Sun” 10% 11% 60% 11%

Normalized Gain “Sun” 0 0 0.58 0

Table 5.10. Q 5; high school basic biology classes’ normalized gains of the correct response, “sun”. Class H07 (shaded) had a significant gain after instruction.

5.1.3. Misconception 3: Source of biomass (carbon) in plants (Questions 6a and 6b) Question 6 assessed students’ understanding that plants use carbon dioxide from the atmosphere. Question 6 has two parts; the first part (Q 6a) asked students to identify that photosynthesis reduced the amount of carbon dioxide into the atmosphere.

5.1.3.1. Source of biomass (carbon) in plants: Question 6a Q 6a. What effect does photosynthesis have on carbon dioxide in the atmosphere? A. B.

C.

Photosynthesis increases carbon dioxide in the atmosphere Photosynthesis decreases carbon dioxide in the atmosphere* Photosynthesis has no effect on carbon dioxide in the atmosphere

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5.1.3.1.1. Middle school responses to Q 6a Class M06 was the only class that answered the pre- and post-surveys with a significant difference (Figure 5.10). Class M06 gained after instruction with a normalized gain of 0.41 (Table 5.11). In all classes, the most popular answer was the correct answer, “carbon dioxide decreases”.

Class M06 n = 72 = 0.41

Figure 5.10. Q 6a; middle school class M06 answered significantly differently on the post-survey and gained in the correct response (*) after instruction. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars). Class

Pre-Survey “Decreases”

Post-Survey “Decreases”

Normalized Gain “Decreases”

M01 M03 M04 M05 M06

71% 59% 66% 60% 49%

73% 59% 66% 67% 70%

0.06 0 0 0.17 0.41

Table 5.11. Q 6a; middle school classes’ normalized gains in the correct answer that photosynthesis decreases atmospheric carbon dioxide. Class M06 (shaded) was the only class that had a significant change.

5.1.3.1.2. High school responses to Q 6a The high school advanced and basic biology classes did not answer this question significantly differently and were grouped together by teacher. Classes H04 and H07 answered the pre- and post-survey significantly differently (Figure 5.11). However, in 44

class H04, there was no change in the correct answer. Instead, there was a shift to the incorrect answer, “carbon dioxide increases,” after instruction from 11% to 33%. While class H07 had a normalized gain in the correct answer of 0.14 (Table 5.12). The correct answer was the most common answer in both the pre- and post-surveys in all classes.

Class H04 n = 18 = 0

ClassH07 n = 25 = 0.14

Figure 5.11. Q 6a; high school classes H04 and H07 answered the post-survey significantly different than the pre-survey. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars), correct response (*). Class H02 H04 H07 H08

Pre-Survey “Decreases” 90% 61% 72% 79%

Post-Survey “Decreases” 100% 61% 76% 79%

Normalized Gain “Decreases” 1.00 0 0.14 0

Table 5.12. Q 6a; high school basic biology classes’ normalized gains in the correct answer, “carbon dioxide decreases”.

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5.1.3.2. Source of biomass (carbon) in plants: Question 6b Q 6b. Explain your reasoning. (To question 6a)

Question 6b asked the students to explain their reasoning as to how they answered question 6a. Responses were then coded into four categories: no response (0), incorrect (1), partially correct (2), or correct (3). If this question was left blank or if a student answered using some form of, “I don’t know,” then the answer was considered a, “no response.” The most popular, “incorrect” reasoning was that plants release carbon dioxide. Some responses fell under, “partially correct.” The most common, partially correct response was that plants “breathe” carbon dioxide. Most middle and high school students answered with a, “correct,” response on the pre- and post-surveys giving the reasoning, plants take in carbon dioxide from the air for photosynthesis.

5.1.3.2.1. Middle school responses to Q 6b Classes M04, M05, and M06 answered the pre- and post-surveys differently at a 95% significance level (Figure 5.12). Their normalized gains were 0.54, 0.31, and 0.53, respectively (Table 5.13). The correct reasoning was the most popular response after instruction.

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ClassM04 n = 40 = 0.54

Class M05 n = 75 = 0.31

ClassM06 n = 77 = 0.53

Figure 5.12. Q 6b; middle school classes M04, M05, and M06. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars).

Class M01 M03 M04 M05 M06

Pre-Survey 46% 56% 15% 48% 34%

Post-Survey 59% 63% 61% 64% 69%

Normalized Gain 0.25 0.17 0.54 0.31 0.53

Table 5.13. Q 6b; middle school classes’ normalized gains in the correct reasoning. Classes M04, M05, and M06 had significant gains after instruction. 5.1.3.2.2. High school responses to Q 6b The high school advanced and basic biology classes answered the post-survey significantly differently and are thus presented separately. Basic biology classes: Neither basic biology class answered the pre- and post-survey with a significant difference (Table 5.14).

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Class

Pre-Survey

Post-Survey

Normalized Gain

Basic H04

39%

33%

-0.09

Basic H08

50%

50%

0

Table 5.14. Q 6b; changes in high school basic biology classes were significant. Advanced biology classes: None of the advanced biology classes had significant changes after instruction. Classes H02 and H07 gained after instruction while class H08 did not change (Table 5.15). In all classes, the most popular response on both the pre- and post-surveys was the correct reasoning. Class

Pre-Survey

Post-Survey

Normalized Gain

Advanced H02

90%

100%

1.00

Advanced H07 Advanced H08

60% 57%

76% 57%

0.40 0

Table 5.15. Q 6b; high school advanced biology classes’ normalized gains in the correct reasoning. None of the changes were significant.

5.1.4. Misconception 4: Cellular respiration in plants (Questions 7 and 8) Several common student misconceptions have been identified about cellular respiration. I decided to focus on two of them: plants and animals respire and cellular respiration occurs within all cells. I used Question 7 to assess students’ understanding that both plants and animals respire. Question 8 assessed students’ understanding that cellular respiration occurs in all cells. 5.1.4.1. Cellular respiration in plants: Question 7 Q 7. Humans engage in respiration; which other living things engage in respiration? (Check all that apply) A. Snail B. Bacteria C. Rose plant D. Cow E. Mushroom F. All of the above

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Question 7 required students to recognize that plants and animals undergo cellular respiration. The correct response was, “all of the above,” which included snail, bacteria, rose plant, cow, and mushroom. Students were also given the option to pick any combination that they thought was correct. The misconception that only animals undergo cellular respiration would be evident in the combination, “snail and cow.”

5.1.4.1.1. Middle school responses to Q 7 Class M04 was the only class that answered the pre- and post-surveys significantly differently (Figure 5.13). Class M04 also gained in the correct answer after instruction (Table 5.16). In most classes, the most popular response was the correct response, followed by the combination, “snail and cow.”

Class M04 n = 41 = 0.13

Figure 5.13. Q 7; middle school class M04 was the only class with a significant gain after instruction. Normalized gains (), number of students (n), pre-survey (black bars), post-survey (grey bars), correct response (*). Class M01 M03 M04 M05 M06

Pre-Survey “All of the above” 58% 33% 41% 20% 48%

Post-Survey “All of the above” 51% 26% 49% 33% 57%

Normalized Gains “All of the above” -0.16 -0.11 0.13 0.17 0.18

Table 5.16. Q 7; middle school classes’ normalized gains in the correct answer, “all of the above”. Class M04 (shaded) had the only significant change after instruction.

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5.1.4.1.2. High school responses to Q 7 The high school advanced and basic biology classes did not answer this question significantly differently and were grouped together by teacher. Class H07 was the only class to answer the post survey significantly different than the pre-survey, and exhibited a lost after instruction with a normalized gain of -0.67 (Figure 5.14; Table 5.17). The most popular response on the pre- and post-surveys in all classes was the correct answer, “all of the above.”

Class H07 n = 25 = -0.67

Figure 5.14. Q 7; high school class H07 had p-value < 0.10 and lost in the correct response (*) after instruction. Normalized gains (), number of students (n), presurvey (black bars), post-survey (grey bars). Class H02 H04 H07 H08

Pre-Survey “All of the above” 60% 67% 76% 47%

Post-Survey “All of the above” 60% 39% 60% 53%

Normalized Gains “All of the above” 0 -0.83 -0.67 0.10

Table 5.17. Q 7; high school classes’ normalized gains in the correct response, “all of the above”. Class H07 (shaded) was the only class with a significant change.

5.1.4.2. Cellular respiration in plants: Question 8 Q 8. Where in the human body does respiration take place? (Check all that apply) A. Muscles B. Stomach C. Lungs D. Skin E. Brain F. All body cells

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Question 8 asked students to recognize cellular respiration as a process that occurs within all body cells. The correct response was, “all body cells,” while the common misconception was “lungs.”

5.1.4.2.1. Middle school responses to Q 8 Middle school class M05 was the only class to answer this question significantly different on the post-survey, and showed a gain after instruction with a normalized gain of 0.39 (Figure 5.15; Table 5.18). The most common response on the post-survey was the correct response, “all of the above,” while the next most common answer was the response, “lungs.”

Class M05 n = 75 = 0.39

Figure 5.15. Q 8; middle school class M05 had a significant gain in the correct response (*) after instruction. Normalized gain (), number of students (n), pre-survey (black bars), post-survey (grey bars). Class M01 M03 M04 M05 M06

Pre-Survey “All of the above” 44% 44% 56% 32% 29%

Post-Survey “All of the above” 41% 59% 44% 59% 34%

Normalized Gains “All of the above” -0.06 0.27 -0.28 0.39 0.07

Table 5.18. Q 8; middle school classes’ normalized gains in the correct answer, “all body cells”. Class M05 was the only class with a significant change after instruction.

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5.1.4.2.2. High school responses to Q 8 The high school advanced and basic biology classes did not answer this question significantly different and were grouped together by teacher. None of the high school classes answered the survey significantly differently after instruction and are located in Appendix F. The most popular answer on the post-surveys was the correct response, “all of the above,” however, the next common response was the misconception, “lungs” (Table 5.19). Class H02

Pre-Survey “All of the above” 40%

Post-Survey “All of the above” 60%

Normalized Gains “All of the above” 0.33

H04 H07 H08

44% 80% 89%

56% 76% 63%

0.20 -0.20 -2.5

Table 5.19. Q 8; high school classes’ normalized gain in the correct answer, “all body cells”. None of the changes were significant.

5.2. Teacher pre-survey: How is photosynthesis taught? 5.2.1. Middle school teachers A total of eight middle school teachers completed the teacher survey about how they plan to teach photosynthesis (Appendix C). Five middle school teachers completed the entire study (shaded in grey in Table 5.20). I asked teachers how long they have been teaching, and responses ranged between 2 and 33 years. The length of time each teacher was planning to spend on photosynthesis ranged from 2 to 20 days. The materials that middle school teachers were using varied between classes, including: textbooks, online resources, magazine articles, non-fiction books, and videos. The activities that middle

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school teachers planned to use also varied and included: collecting phytoplankton, using microscopes, art projects, and no activities at all. The concepts that each teacher planned to emphasize during their photosynthesis units were similar to one another, and included the concepts of the Law of Conservation of Matter, source of atmospheric oxygen, primary producers, the chemical equation for photosynthesis, connection between photosynthesis and cellular respiration, and a plant’s energy source. Teachers also identified any concepts their students typically struggled with. The difficult concepts were centered on concepts that require students to think at the molecular level, and included the Law of Conservation of Matter, concept of “food,” and cellular respiration. Other concepts that teachers claimed students struggle with had to do with understanding chemistry; these concepts included the balanced chemical equation for photosynthesis, cellular respiration is the reverse process of photosynthesis, and plants make their own food. Teacher

Years

Time

Materials

Activities

Targeted Concepts

M01

33

3+ days

Review the CO2-O2 cycle, raw materials needed, products and by-products.

Collect plankton (both phyto- & zoo-); model of a marine food web; CD-ROM "Phytopia"

5-10 days

Prentice Hall; interactive word wall; magic border; interactive websites

None

Energy is converted to matter & matter to energy; without photosynthesis life forms could not exist; Earth's oxygen content is the result of photosynthesis; "base of the food chain" & primary producers, for terrestrial & marine ecosystems Chemical formula; components of photosynthesis; how it supports life on earth

M02

3

Difficult Concepts Balanced chemical equation for photosynthesis; matter is neither created nor destroyed, just changed

Plants supply oxygen to humans, not the reverse of respiration, the concept of "food"

Table 5.20. Middle school teachers’ responses to the survey about how they teach photosynthesis. Teachers M01, M03, M04, M05, and M06 (shaded) completed the study. Materials and activities varied among middle school teachers. 53

Teacher

Years

Time

M03

10

15 days

M04

2

M05

Materials

Activities

Targeted Concepts

None

Cell study; readings; art project showing the cycle

15 days

Readings; graphic organizer for vocab

Graphic organizer; class discussion

26

2 days

Beyond Books.com online textbook

None

M06

4

2-3 days

None

Leaf chromatogr aphy

Interconnection between photosynthesis & respiration; takes place on the cellular level; interconnection between photosynthesis & the world's food chains Where plants get energy; where animals get energy; key terms used: chlorophyll, respiration, glucose, phototroph, xylem, stomata, guard cells, and external stimuli Photosynthesis & respiration are reverse processes; plants use oxygen; most plant matter comes from air & solar energy Inputs & outputs; role of producers in the food chain; differences between plant & animal cells

M07

7

Not given

No response

M08

11

15-20 days

Holt series; nonfiction books; magazines; Newbridge Reading Quest series; Internet Webquests; videos; articles

Students build a model of a plant; elodea plants are submerged in bromthymo l blue

Continued.

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Relationship between sun, water, & CO2; end product benefits the plant & other living organisms; investigate what happens in the presence of dark & light, & how this impacts photosynthesis Photosynthesis uses waste products of cellular respiration to create a material used by cellular respiration

Difficult Concepts That it happens on a molecular level

Chemistry of the photosynthesis equation itself

Plant matter comes from air; plants need oxygen Cellular respiration is the same formula in reverse; plants undergo respiration Chemistry

Glucose stores energy used by the cells. Glucose is Matter & Energy. Plants don't "make" energy, they just put it in a form the cells can use. Oxygen isn't energy

5.2.2. High school teachers A total of eight high school teachers completed the teacher survey about how they planned to teach photosynthesis, with only four completing the entire study (shaded in grey in Table 5.21). The teachers’ experiences ranged from eight to fifteen years of teaching. Teachers planned to spend any where from five to fifteen days teaching photosynthesis. All of the high school teachers used a textbook by either Campbell/Reece, Prentice Hall, or BSCS Biology textbooks. Each teacher was planning to perform some type of laboratory experiment. Examples include: plant chromatography, spectrophotometry, microscope investigations, and experiments with Elodea plants. One teacher stipulated use of computer simulations, videos, or games. The concepts that the high school teachers teach during their photosynthesis unit included the details of photosynthesis and were similar to one another. The most common were the chemical equation/process, connection between photosynthesis and cellular respiration, how different factors affect the rate of photosynthesis, light and dark reactions, evolutionary development of photosynthesis, and the global impact of photosynthesis. The most common concepts that students struggle with were the connection between cellular respiration and photosynthesis, the chemical process of photosynthesis including their reactants and products, the Calvin Cycle, and the “big picture” of photosynthesis.

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Teacher

Years

Time

Materials

Activities

Targeted Concepts

H01

5

10 days

Campbell/ Reece

AP Biology Lab

Steps + information necessary for AP exam

H02

10

15 days

Campbell Biology 8th ed; Online tutorials & simulation s; video

The chemical process of photosynthesis; plant & chloroplast anatomy; role of CO2 & water in; the relatedness of photosynthesis to cellular respiration; the evolutionary development of photosynthesis

H03

23

Not given

Various materials from different sources; our text

H04

15

5 days

Prentice Hall Biology

Spectrophotomet er lab; chromatography lab; CAM plant that links acid production to light & dark environment; elodea lab examining CO2 & light as limiting factors; DPIP lab to examine electron transfer during photosynthesis Investigate the structure of plant cells using microscopes, and chromatography; sugar content in different colors of leaves; respiration Computer simulation to show the light & dark reactions; short movie

H05

6

5-7 days

Prentice Hall, Exploring Life

Chromatography activity

Difficult Concepts The steps they get confused about that happens and when it happens The chemical process of photosynthesis ; link between photosynthesis & cellular respiration.

A lot of variables can effect the rate; we depend upon it so we can carry out respiration

Understanding the reactants & products in the equation

Photosynthesis is the opposite of respiration; more than plants photosynthesize; light & dark reactions; equation for photosynthesis; major factors that effect the rate of photosynthesis. Equation of photosynthesis; relate it to cellular respiration; global impact of photosynthesis & how it relates to the carbon cycle & greenhouse effect

Concentrating on the big picture & get hung up on little details; dark is not necessary for the dark reaction Individual reactions involved; Calvin Cycle

Table 5.21. High school teachers’ responses to the survey about how they taught photosynthesis. Teachers H02, H04, H07, and H08 (shaded) completed the study. Materials and activities among high school teachers were similar.

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Teacher

Years

Time

Materials

Activities

Targeted Concepts

H07

11

10 days

Campbell/ Reece

Plant game; stomata lab, plant a plant in a jar; leaf disk assay

Inputs & outputs; where in the plant & cell each part of photosynthesis occurs; factors that effect photosynthesis; interrelatedness between cellular respiration & photosynthesis & how they form a complete cycle

H08

8

10-15 days

Modern Biology Holt (1998) Biology; Exploring Life Prentice Hall

H09

15

7-12 days

BSCS Biology: A Molecular Approach

AP Bio: chromatography /absorption spectra pigment lab & a lab that measures the light reactions Photosynthesis pigment lab (chromatography ); elodea photosynthesis rate lab

Design & perform experiments with Elodea to discover if plants need light, use CO2, give off O2 & give off some CO2 (respiration); design & perform experiments with Elodea; design experiments exploring the effects of temperature on rate.

Continued.

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Cyclical nature of photosynthesis & cellular respiration; parts of the cell where different steps occur; reactants & products of the overall process; individual steps; modifications in plants (alternate pathways); how temp, CO2, & light intensity effect photosynthetic rate Connection of photosynthesis (or chemosynthesis) to all living organisms; kinds of things effect its rate; specializations & adaptations

Difficult Concepts Details of the photosystems, electron transport chain, & chemiosmosis

Function of individual photosystems; "driving force" to ATP production

What goes in & what comes out at which point.

5.3. Research Question 2: Measuring teachers’ pedagogical content knowledge (PCK) The teacher PCK survey was identical to the student post-survey with the exception that teachers were asked to predict their students’ responses by predicting whether “most,” “some,” or “few/none” of their students would choose each answer. These predictions were then compared to the students’ post-survey to determine if the teacher’s prediction matched his or her students’ responses, or if it was an over- or underprediction. To be considered a match for “most,” the majority of their students must have selected that response, a match for “some” was greater than 5% of their students, and a match for “few/none” was equal to or less than 5% of their students. Analysis was complicated because some teachers selected the option “most” more than once for each question. In this case, the incorrect, “most,” prediction was counted as an overprediction. Complete tables of each teacher’s predictions are located in Appendix G. The following section presents middle and high school teachers’ predictions of their students’ responses to the correct option for each question.

5.3.1. Middle school teachers 46% of the middle school teachers’ predictions matched their students’ responses, while 34% were over-predictions, and 20% were under-predictions (Table 5.22).

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Teacher M01 M03 M04 M05 M06 Overall

Matched Prediction Correct option 43% 43% 43% 75% 29% 46%

Over Prediction Correct option 43% 43% 29% 15% 43% 34%

Under Prediction Correct option 14% 14% 28% 14% 28% 20%

Table 5.22. Middle school teachers’ predictions (correct option only). Approximately half of the predictions matched students’ responses, 34% were over-predictions, and 20% were under-predictions.

5.3.2. High school teachers 57% of high school teachers’ predictions matched their students’ responses, 25% were over-predictions, and 18% were under-predictions (Table 5.23). Teacher H02 H04 H07 H08 Overall

Matched Prediction Correct option 57% 71% 57% 43% 57%

Over Prediction Correct option 14% 14% 29% 43% 25%

Under Prediction Correct option 29% 15% 14% 14% 18%

Table 5.23. High school teachers’ predictions (correct option only). 57% of the predictions matched student responses, 25% were over-predictions, and 18% were underpredictions.

5.3.3. Teachers’ predictions by question Considering all of the middle and high school classes and all multiple-choice questions in the student survey, there were 63 opportunities for a class to experience a gain, a loss, or no change. A total of 20 losses and 34 gains were recorded in students’ understanding after instruction (Table 5.24). Out of the 20 losses, 30% of the predictions for the correct option matched students’ responses, and 70% were either over-predictions

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(30%) or under-predictions (40%). Among the 34 gains in students’ understanding across all classes and questions, 62% of the predictions for the correct option were matches, while 40% were either over-predictions (24%) or under-predictions (14%). All the teachers’ predictions are located in Appendix G. Normalized Gain Gain (34) Loss (20) No Change (8)

Matched 61.8% 30.0% 50.0%

Over-Prediction 23.5% 30.0% 37.5%

Under-Prediction 14.7% 40.0% 12.5%

Table 5.24. Predictions compared to students’ responses, 9 teachers x 7 questions = 63 opportunities for a match. When a teacher matched their prediction to his or her students’ responses, the class was more likely to experience a gain after instruction.

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Chapter 6 DISCUSSION

My study has uncovered two main findings: 1) Most middle and high school students in my study did not have the conceptual knowledge about photosynthesis that is expected according to national and state science standards, and 2) Classes that experienced gains in understanding after instruction were more likely taught by teachers with higher pedagogical content knowledge scores. These findings are discussed in detail in the following pages, as well as the implications of these findings, and the limitations of my study. 6.1. Finding 1: Most middle and high school students in my study did not have the conceptual knowledge about photosynthesis expected according to national and state standards Most students in my study did not understand five major concepts about photosynthesis: 1) the energy for photosynthesis comes from sunlight, 2) plants use carbon dioxide from the atmosphere for the production of carbohydrates, 3) photosynthesis occurs within all cells that contain chlorophyll, 4) plants use the glucose formed during photosynthesis to fuel cellular respiration, and 5) cellular respiration occurs within all living cells. These five concepts are found in the Maine Learning Results, and in the National Science Standards at both the middle and high school levels, and all students are expected to know and understand them by the time they graduate. In this chapter, these concepts will be individually discussed.

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For my study, it is assumed that a class largely understands a concept if the mean class score is 70% or better. Other assessments also use this threshold to indicate proficiency. For example, the proficient level under the New England Common Assessment Program (NECAP) is 70%. The NECAP standards of proficient are used in New Hampshire, Vermont, Rhode Island, and most recently Maine (math and language arts only), to demonstrate that students are meeting the standards as described in the “No Child Left Behind Act.”

6.1.1. Misconception 1: Only leaves photosynthesize Middle and high school students in my study did not correctly identify that photosynthesis occurs in any cell that contains chlorophyll (Table 6.1). The most common incorrect choice for Question 1 was that photosynthesis occurs in the leaves. The most common incorrect choice for Question 2 was that chlorophyll is located in the leaves of the plant. While this answer is not entirely incorrect because photosynthesis does primarily occur in the leaves, it suggests that students did not fully understand the connection between photosynthesis and chlorophyll. A question asked of 8th graders in 2004 by the Maine Educational Assessment (MEA) about the function of chloroplasts supports this finding because they found that only 62% of students knew that photosynthesis occurs in chloroplasts (Table 6.2).

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Source MLR

Level Middle School

NSS

High School

MLR

High School

MLR

High School

Standard Describe how external and internal structures of animals and plants contribute to the variety of ways organisms are able to find food and reproduce. Plant cells contain chloroplasts, the site of photosynthesis. Identify structures that help organisms to stay alive. Describe the similarities and differences in the basic functions of cell membranes and the specialized parts within cells that allow them to capture and release energy.

% Students in my study w/ conceptual understanding 35% of Middle School Students

43% of High School Students

Table 6.1. Middle and high school standards relating to chlorophyll and photosynthesis. Students in my study did not have the conceptual understanding that is required. MLR: Maine Learning Results, NSS: National Science Standards. Items in italics were not tested.

2004 8th Grade MEA Question Which function do cells containing chloroplasts perform in an organism? A. Photosynthesis (62%) B. Transpiration C. Condensation D. Diffusion

Question 1 & 2 from the student survey 1. Where in the plant does photosynthesis take place? A. Photosynthesis takes place in the roots B. Photosynthesis takes place in the leaves C. Photosynthesis takes place in all green parts of the plant D. Photosynthesis takes place in the whole plant 2. Where in the plant are chloroplasts located? A. Chlorophyll is in the roots B. Chlorophyll is in the leaves C. Chlorophyll is in the green parts of the plant D. Chlorophyll is in the whole plant Cross Analysis: 1. Green parts/Green parts (11%) 2. Leaves/Leaves (24%) 3. Whole plant/Whole plant (3%) 4. Other Combination (62%)

Table 6.2. 2004 8th grade MEA question compared to Q 1 and Q 2 from the middle school student post-survey. The correct answer is in bold along with the percentage of students who answered it correctly.

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How much do students understand about photosynthesis and the function of chlorophyll and chloroplasts? I believe the next step in investigating this concept would be to ask middle and high school students the same two questions from this investigation, but add a third question about chloroplasts and combine them into the following: Choose the best answer to the following questions: 1. Where in plants does photosynthesis take place? A. The roots B. The leaves C. All green parts D. The whole plant

2. Where in plants is chlorophyll located? A. The roots B. The leaves C. All green parts D. The whole plant

3. Where in plants are chloroplasts located? A. The roots B. The leaves C. All green parts D The whole plant

Explain your reasoning.

6.1.1.1. Recommendations for teaching all cells that contain chlorophyll photosynthesize Students’ misunderstanding about the connection between chlorophyll, chloroplasts, and photosynthesis could be due to the types of figures and activities used when teaching photosynthesis. One of the first diagrams that middle and high school students see when learning about photosynthesis is one that focuses on the leaves of the plant (Figure 6.1a to 6.1c). This type of figure either shows photosynthesis occurring only in the leaves, or emphasizes the leaves with arrows going into and out of them, and could lead students to the conclusion that photosynthesis only takes place in the leaves. I suggest avoiding this type of figure all together and use figures depicting algae or figures that show any part of the plant containing chlorophyll will photosynthesize. Teachers could also use alternative lessons that avoid using leaves altogether. For example, students could study plants without leaves, such as cacti or single cell algae. Teachers

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could teach photosynthesis without using plants at all by investigating the photosynthetic sea slug, Elysia chlorotica (Rumpho et al. 2008). Sea slugs eat green algae and incorporate the plant’s chloroplasts into its own body. Afterwards, the sea slug can live for several months on the photosynthesis of the stolen chloroplasts. These alternative methods provide students with several other examples to draw from in order to connect photosynthesis to the chlorophyll located within chloroplasts.

Figure 6.1. Figures showing basic descriptions of photosynthesis focusing on the leaves of the plant, similar figures are found in many middle and high school textbooks a) From Merriam-Webster online dictionary accessed in June 2010.

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Figure 6.1: Continued

b) From Campbell and Reece (2002).

c) From Glencoe Biology (2009).

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6.1.2. Misconception 2: Plants use multiple energy sources Middle and high school students in my study attributed the energy source for photosynthesis to multiple sources instead of one source, light. Most students attributed a plant’s energy source to multiple sources such as air, water, soil, and/or fertilizer (Table 6.3). This misunderstanding might be explained by students’ insufficient knowledge of chemistry, the Law of Conservation of Energy and that plants convert light energy into chemical energy (Stavy et al. 1987; Eisen and Stavy 1988; Anderson et al. 1990; Waheed and Lucas 1992; Canal 1999; Carlsson 2002a; Lin and Hu 2003; Ozay and Oztas 2003; Marmaroti and Galanopoulou 2006). Source

Level

NSS

Middle School

MLR

Middle School

MLR

Middle School

NSS

High School

NSS

High School

Standard For ecosystems, the major source of energy is sunlight. Energy enters ecosystems as producers transfer sunlight into chemical energy via photosynthesis. That energy then passes from organism to organism in food webs. Describe the source and flow of energy in the two major food webs, terrestrial and marine. Describe how matter and energy change from one form to another in living things and in the physical environment. Plants and many microorganisms use solar energy to combine molecules of carbon dioxide and water into complex, energy rich organic compounds and release oxygen to the environment. The energy for life is primarily derived from the sun.

% students w/ conceptual understanding

12% of Middle School Students

10% of High School Students

Table 6.3. Middle and high school standards relating to light and photosynthesis. Students in my study did not have the conceptual understanding that is required. MLR: Maine Learning Results, NSS: National Science Standards.

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Another contributing factor to this misconception could be students’ knowledge about human consumption of food (Eisen and Stavy 1988; Canal 1999; Lin and Hu 2003; Marmaroti and Galanopoulou 2006). Humans consume food for nutrients and energy, while plants consume carbon dioxide, water, and other nutrients from the soil to increase biomass, but obtain the energy to do so from the sun. Evidence that students may not understand the difference between nutrients and energy comes from the combination of energy sources that students chose in addition to the sun. In Question 5 of this survey, the most popular combination of energy sources among middle and high school students was “all of the above” (sun, water, air, soil, and fertilizer), followed by the combination “air, water, and sun,” the reactants necessary for photosynthesis. Students may be likening plant consumption of water and air to human consumption of food by grouping food, nutrition or nutrients, and energy as one and the same. There also seems to be a correlation between how the question is asked and the level of understanding measured. My study used a multiple-choice, multiple-response question so that students could choose a single energy source or a combination of energy sources, and I found a decreased frequency of correct responses among middle and high school students compared to studies that used multiple choice questions. Studies by Ozay and Oztas (2003) and Waheed and Lucas (1992) also asked questions about the energy source for photosynthesis in which students could choose more than one energy source, and they also found lower rate of correct responses. However, questions asked in Marmaroti and Galanopoulou’s (2006) and an MEA question in 2002 only allowed students to choose one energy source and measured higher frequency of correct responses, about 80% (Table 6.4). Multiple-choice questions with only one option

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seemed to show a higher frequency of correct responses compared to questions that allowed students to choose more than one energy source. What is the best way to write a good question that assesses students’ understanding of the energy source for photosynthesis? Data from my study, MEA results, and published research, suggests that when asking about the energy source for photosynthesis, the most common misconception is that energy comes from multiple sources. Therefore, asking students a question in which students have the option of choosing a single energy source or multiple energy sources will likely uncover whether or not that population of students has the misconception that plants receive energy from multiple sources. The question could go further in uncovering students’ understanding by asking students to explain their reasoning for their choices. 2002 8th Grade MEA Question Plants get the energy they need to live and grow from: E. Air F. Soil G. Water H. Sunlight (78%)

Question 5 from my survey A bean plant needs energy to survive and grow. Where does that energy come from? (Check all that apply) A. Air (1%) B. Water (1%) C. Sun (12%) D. Soil (1%) E. Fertilizer (0%) F. All of the above (40%) The numbers shown here are the percentage of students who only chose one of these options. Many students chose a combination of sources.

Table 6.4. Comparison of 2002 MEA 8th grade question and Q 5 from the middle school student post-survey about a plant’s energy source. The correct answer is in bold with the percentage of students who answered it correctly. There may also be confusion about the energy source for mature plants and the energy source during seed germination. During germination, plants use the energy stored within the seed itself to fuel cellular respiration to grow in order to reach through the soil

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to sunlight. While undergoing cellular respiration at this time, the plant’s mass actually decreases until it reaches the surface and begins to photosynthesize. At this point, the plant will begin to increase in size and mass. Do students understand the difference between photosynthesis and cellular respiration? In order to assess students’ understanding about these concepts I recommend using the following question: Which of the following processes occurs in a seed during germination? A. Photosynthesis B. Cellular Respiration C. Both

D. Neither

Where does a plant get its energy during germination?

6.1.2.1. Recommendations for teaching light is the only energy source for photosynthesis In many classrooms, students are taught photosynthesis through a series of lectures followed by a laboratory exercise using aquatic plants or even isolating chloroplasts (Tables 5.20 and 5.21). However, often students do not connect what they learned in lecture to what they are doing during hands on activities (Ross et al. 2005). Supplementing lectures with different types of activities is important to reach different types of learners in the classroom. Activities such as group discussions, online “web quests,” and even concept mapping has been shown to be effective methods for teaching difficult concepts like photosynthesis (Novak 1995; Baggott la Velle 2000; Brown 2003). Studies show that students reach a higher level of understanding while confronting misconceptions through inquiry-based activities (Amir and Tamir 1994; National Research Council 2000; Carr 2001; Thompson 2007; O’Connell 2008; Ray and Beardsley 2008). The highest level of inquiry will have students actively engaged in an investigation that is largely student driven while the instructor takes a back seat during

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the lesson. In many inquiry-based activities, students confront their misconceptions and are given the opportunity to correct their thinking to the scientifically accepted explanation of the concept that they are learning. Thompson (2007), O’Connell (2008), and Ray and Beardsley (2008) outline different inquiry-based activities relating photosynthesis to cellular respiration. All of these activities show an increase in student engagement and understanding about photosynthesis. Each activity also provides adjustments for different age levels and achievement so the activity can be adapted for any classroom.

6.1.3. Misconception 3: Plants obtain biomass through the uptake of soil High school students in my study correctly identified that plants use carbon dioxide from the atmosphere and release oxygen, while most middle school students did not. Conversely, an MEA question asked of 8th graders in 2005 showed that middle school students did understand that air was needed for photosynthesis (Table. 6.5). 2005 8th Grade MEA Question Plants need water and sunlight for photosynthesis. What else is necessary for photosynthesis to occur? E. Air (75%) F. Sulfur G. Iron H. Nitrogen

Question 6a & 6b from my survey 6a. What effect does photosynthesis have on carbon dioxide in the atmosphere? A. Photosynthesis increases carbon dioxide in the atmosphere (18%) B. Photosynthesis decreases carbon dioxide in the atmosphere (67%) C. Photosynthesis has no effect on carbon dioxide in the atmosphere (15%) 6b: Explain your reasoning. No response (11%) Incorrect (18%) Partially correct (8%) Correct (63%)

Table 6.5. 2005 8th grade MEA question compared to Q 6a and Q 6b from the middle school student post-survey. The correct answer is in bold with the percentage of students who answered it correctly.

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Previous research has suggested that it is difficult for students to understand how plants use carbon dioxide for various reasons. First, carbon dioxide is used during photosynthesis to produce glucose. The idea of a gas (carbon dioxide) producing a solid material (glucose) is a difficult concept for students to grasp. It requires students to identify gas as matter that has mass and takes up space. Therefore, it must obey the Law of Conservation of Matter, which is often difficult for students (Lin and Hu 2003; Marmaroti and Galanopoulou 2006). Second, students must confront what they previously understood as “food.” Many students believe that while plants undergo photosynthesis, they must also consume “food,” which is usually interpreted as materials such as soil, water, or fertilizer (Simpson and Arnold 1982; Bell 1985; Barker and Carr 1989a; Barker and Carr 1989b; Ozay and Oztas 2003; Ebert-May et al. 2003; Marmaroti and Galanopoulou 2006). However, through the use of the questions in this survey, it is unclear whether or not students understand the processes that happen in between taking in carbon dioxide and expelling oxygen.

6.1.3.1. Recommendations for teaching plant biomass comes from carbohydrate production during photosynthesis High school students in my study correctly identified that photosynthesis decreases the amount of carbon dioxide in the atmosphere; however, do they understand what plants do with carbon dioxide after it is taken in? I recommend the following new question to uncover student thinking about how plants grow. A plant’s body mass is made up of carbon-based molecules. Where does that carbon come from? A. Air B. Water C. Sun D. Soil E. Fertilizer F. All of the above Explain your reasoning.

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6.1.4. Misconception 4: Cellular respiration only occurs in animals Middle and high school students in my study did not identify that cellular respiration occurs in plants, and that it occurs at the cellular level (Table 6.6). These results are similar to that of a study performed by Simpson and Arnold (1982), who surveyed high school students about their understanding of cellular respiration during a photosynthesis unit. They found that students did not identify that plants undergo cellular respiration. However, Seymore and Longden (1991) surveyed high school students about cellular respiration during an animal unit and found that those students did identify that all plants and animals undergo cellular respiration. It is possible that students are better able to understand cellular respiration while learning about animals but are unable to find the connection between cellular respiration and photosynthesis during the photosynthesis unit because cellular respiration is often thought of as a process that only occurs in animals. Source MLR

Level

Standard

High School Describe the similarities and differences in the basic functions of cell membranes and of the specialized parts within cells that allow them to capture and release energy.

% students w/ conceptual understanding 60% of High School Students

Table 6.6. High school Maine Learning Result relating to cellular respiration and photosynthesis. Students in my study did not understand this concept. Concept in italics was not tested. The context in which cellular respiration is used may affect the rate of correct answers given. There is a difference between “cellular respiration” and “respiration.” Respiration is the act of breathing and the intake of oxygen in animals, while cellular respiration refers to the process of breaking down glucose into energy. Animals undergo

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both cellular respiration and respiration, while plants only undergo cellular respiration. It is important to make this difference known in order to be sure that the correct concept is being assessed. All of the studies mentioned here, including my study, used the term “respiration.” This could have misled students to think about the act of breathing instead of the cellular process that occurs in plants and animals.

6.1.4.1. Recommendations for teaching cellular respiration and photosynthesis Middle and high school students in my study did not correctly identify that cellular respiration occurs within plants, or that cellular respiration occurs within all cells. An activity outlined in O’Connell (2008) confronts students’ misconceptions regarding the energy source for photosynthesis and cellular respiration within plants. The activity asks students to find the mass of a pea and then to germinate it in a small pan of shallow water. The students are then asked to hypothesize how the plants are growing, where they are getting the energy to do so, and if they believe the pea will increase or decrease in mass as they germinate. Many students will hypothesize that the pea will increase in mass as they germinate because they appear to grow larger in size. The students then dry out the seedling and obtain its mass, and will discover that the pea actually decreased in mass, but increased in length. After a group discussion, students should reach the conclusion that during germination, plants undergo cellular respiration by using the energy stored in the cotyledons to grow in size. Plants only begin to increase in mass when they reach the surface and begin to photosynthesize. While this activity is directed toward high school students, it can be simplified for the middle school classroom.

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6.1.5. Implications of my study Middle school students are expected to understand the following concepts; all cells that contain chlorophyll photosynthesize, light is the only energy source for photosynthesis, and a plant’s biomass comes carbohydrates synthesized from carbon dioxide through photosynthesis. High school students are expected to build upon this conceptual base by learning the details of the light and dark reactions, including the electron transport, the production of ATP from ADP, and carbon fixation through the Calvin cycle. The lack of conceptual understanding of photosynthesis among middle school students suggests that incoming high school students may not be entering 10th grade with the conceptual knowledge about photosynthesis that is expected. This finding has several implications for the life science classroom because when students do not have an accurate conceptual understanding of photosynthesis it not only hinders how they understand the details of the light dependent and light independent reactions, but it may also impede their understanding of the role of photosynthesis in the carbon cycle, food webs, and ecosystems. High school teachers could use the revised survey and teacher’s notes in Appendix H to assess their students’ prior knowledge about photosynthesis before instruction. Teachers can then use the information gathered by the pre-survey to fill in the gaps of knowledge so that high school students have an accurate conceptual understanding before delving into the details of photosynthesis. The teacher’s notes also include a summary of common misconceptions, provided teachers with deeper insight into how their students may be thinking about photosynthesis. There are also social implications of citizens being knowledgeable enough about scientific concepts to be able to make informed decisions in the voting booth.

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Photosynthesis is an important part of the global carbon cycle, it draws carbon dioxide out of the atmosphere and incorporates it into biomass (Figure 6.2). When plants and animals die, they are buried deep within the earth’s crust, and after millions of years of being under high pressure and temperature that organic matter may be turned into fossil fuels. Humans then harvest fossil fuels to fuel cars, power plants, and other industrial processes. When fossil fuels are burned, carbon dioxide is expelled instantly into the atmosphere through combustion. A general combustion equation is essentially the same equation as cellular respiration, an organic molecule combusts in the presence of oxygen, forming carbon dioxide, water, and energy: CxHx + O2 → CO2 + H2O + energy

Atmosphere

Oceans Dissolved, Plants, Animals, Shells, etc.

Biomass

Carbon Cycle

Plants & Animals

Subterranean Gas, Oil, Peat, etc.

Figure 6.2. The burning of fossil fuels and other activities expel CO2 into the atmosphere, plants use CO2 during photosynthesis, plants and animals die and are buried and converted to fossil fuels. The thicker arrows indicate a faster exchange between reservoirs.

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Plants can then use the carbon dioxide for photosynthesis, starting the cycle over again. The release of carbon dioxide into the atmosphere and the intake of carbon dioxide by plants are instant processes. However, it takes millions of years to complete the cycle by turning the organic matter into fossil fuels. When humans burn fossil fuels, they are increasing the natural rate at which carbon dioxide being added to the atmosphere, resulting in climate change. Global climate change is directly affected by the amount of carbon dioxide in the atmosphere because carbon dioxide is a greenhouse gas. Greenhouse gases trap the earth’s outgoing radiation, causing the atmosphere to warm. This warming may have several environmental implications, including the melting of ice which could increase sea level in many places, increase the loss of habitat for many species, and/or a change in earth’s weather patterns. Plants play an integral part of the carbon cycle by drawing carbon dioxide from the atmosphere and incorporating the carbon into biomass, therefore, plants also play an integral part in global climate change. If someone does not understand how photosynthesis converts carbon dioxide into biomass, that lack of knowledge would make it difficult for that person to make informed decisions about public policy concerning global climate change and the amount of carbon dioxide being released into the atmosphere (Bord et al. 2000; Fortner et al. 2000; Lowe et al. 2006). A study by O’Conner et al. (2002) found that when someone understood climate change and the factors that affect it, including photosynthesis, they were more likely to support policy to help reduce the amount carbon dioxide in the atmosphere. It is important that young people learn about photosynthesis and its relationship to the carbon cycle and climate change so that they can make informed decisions as adults.

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6.2. Finding 2: Classes with gains after instruction were more likely to be taught by teachers who had high pedagogical content knowledge (PCK) scores. Classes that demonstrated gains in understanding after instruction were more likely taught by a teacher with high PCK scores (matched predictions) (Table 6.7). For classes that experienced gains in understanding after instruction, 62% of their teachers’ predictions matched students’ responses. Conversely, when a class demonstrated a loss in understanding, 70% of their teachers’ responses did not match students’ responses. Normalized Gain

Match

Over-Predict

Under-Predict

Gain (34) Loss (20)

62% 30%

40% 30%

24% 40%

Table 6.7. Classes that gained were more likely taught by a teacher with high PCK. There were 34 total gains and 20 total losses. Teachers over-predicted (meaning they predicted more students would answer correctly than did) their students’ correct responses on Question 5 regarding the energy source for photosynthesis more than any other question (Table 6.8). Question 5 also demonstrated the lowest level of understanding compared to any other question in the student survey. Question 5 required a strong conceptual understanding about the energy source for photosynthesis in order to answer it correctly. Students were asked to identify the energy source for photosynthesis and were able to choose multiple sources, whereas the correct response was the sun only. Most students in my study chose multiple sources. Lightman and Sadler (1993) found that over-predictions and under-performance went hand-in-hand on questions that required any type of conceptual understanding with deep-rooted misconceptions, questions exactly like Question 5 in my study.

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Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match

Over X X X X X X X

X X

Under

0.02 -0.01 -0.03 -0.11 0.16 0 0 0.58 0

Table 6.8. Q 5 teachers’ predictions compared to their class’s normalized gain ().

6.2.1. Recommendations for further study assessing the relationship between teachers’ PCK and student understanding While the results from my study show a correlation between teachers’ pedagogical content knowledge (PCK) and students’ gains in understanding, it might have been better to ask teachers to predict the approximate percentage of students who would choose each choice after instruction. This would have allowed for a more quantitative analysis about teacher PCK and student learning. One could compare teachers’ percentage prediction to the actual percentage from the student post-surveys. From there, the over- and under-predictions could be quantified and compared to students’ gains in understanding after instruction. It could also be helpful to measure teachers’ content knowledge about photosynthesis by asking them to complete the photosynthesis concept survey themselves. Previous studies have shown that K-8 teachers and students have similar understandings or misunderstandings about science concepts (Driver et al. 1985; Osborne and Freyberg 1985; Wandersee et al. 1994; Harlen and Halroyd 1997; Jewel 2002; Rice 2005; Krall and Lott 2009). In fact, the majority of teachers in Krall and Lott’s (1990) 79

study did not have an accurate understanding about the foundational concepts of photosynthesis as outlined in the national standards. It is possible that some teachers in my study held the same misconceptions about photosynthesis that their students did, which would affect how that teacher taught photosynthesis.

6.3. Limitations While it cannot be said that the results of my study are typical of all students, or even all Maine students, the results of my study show that there are some areas of concern regarding photosynthesis education. My study focused on a small sample of middle school (n = 281) and high school (n = 54) students in Maine, who were volunteered to participate by their classroom teacher. Teachers could have had different reasons for volunteering their classes. They could have been interested in education research, photosynthesis education, or even interested in documenting their own teaching. Any of these reasons could cause bias in the study. Teachers actively volunteering who are interested in participating in education research represent a unique population of teachers and do not represent the average classroom. In order to make a more generalizable statement about Maine students, one would need to survey a larger, random sample. One could generate a random sample by setting different parameters, such as school size, socioeconomic status, rural/urban location, length of time teaching, or any other parameter one would like to include. Once the parameters were set, any teacher who is eligible would be invited to participate in the study. While the teacher must still ultimately volunteer, the parameters set would help provide a random sample.

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During my study, I collected information that provided an insight into how photosynthesis was taught. However, there was no clear documentation about what actually happened in the classroom. In hindsight, asking teachers what they did after their instruction would provide more accurate information about what went on in the classroom, as plans may change during a unit. Additionally, because there was such a small sample size of teachers (n = 9), it was impossible to draw conclusions about which materials were more effective. The materials and activities teachers used to teach photosynthesis could be the topic of a future study, as a lot can be learned from how teachers are teaching and what materials they are using. The researcher could split photosynthesis into individual concepts (i.e. energy source, carbon source, location of photosynthesis, and cellular respiration). Before each concept is taught, teachers could administer a pre-survey to their students (a few questions isolating that specific concept), complete the lesson, and then give the students the same post-survey to measure gains in understanding about that concept. Teachers could also complete a survey after instruction to chronicle exactly what they did during that particular concept, including the lessons they used, materials they used, and how long they spent teaching that concept. This could provide a much deeper insight about what is happening in the classroom, and could provide reliable and effective lessons for other teachers to use or even lessons to avoid. Another limitation regarding my study involves the teacher PCK survey. Classes with good students could produce gains in learning after instruction regardless of their teacher, suggesting that there is no correlation at all. Previous studies have suggested that matching teachers’ predictions to their students’ responses could be a way of measuring

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teacher PCK (Lawrenz 1991; Lightman and Sadler 1993). Lawrenz (1991), Lightman and Sadler (1993), and my study suggests there is a positive correlation between matched predictions and student learning. However, more research involving larger sample sizes of teachers’ predictions and gains in student learning need to be done to provide additional evidence for this possible correlation.

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Chapter 7 SUMMARY

Photosynthesis is the most essential process for the sustenance of life on earth because oxygen is produced as a byproduct during photosynthesis. It is also important because photosynthesis converts light energy to chemical energy that can be used by the plant, or an animal that consumes the plant. This conversion of energy becomes the basis of nearly every food web on earth. Photosynthesis is also an important part of the global carbon cycle because plants take in carbon dioxide from the atmosphere and convert it to biomass. It is important for every citizen in a modern democracy to understand how energy and carbon cycles through earth in order to make informed decisions about policies that affect the environment. Therefore, photosynthesis is an important part of middle and high school life sciences curricula, not only to educate students, but to also produce informed adults that could affect environmental policies. My study assessed middle and high school students’ conceptual understanding of photosynthesis, and demonstrated that these middle and high school students did not understand that all cells that contain chlorophyll photosynthesize, sunlight is the only energy source for photosynthesis, plants undergo cellular respiration, and cellular respiration occurs in all cells. However, high school students in my study correctly identified that plants use carbon dioxide from the atmosphere while middle school students did not. The results of my study also suggest a correlation between teachers’ pedagogical content knowledge and their students’ gains in understanding after instruction. Classes

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with gains after instruction were likely taught by teachers who had high pedagogical content knowledge scores (matched teacher predictions). These findings imply that middle school students may not be entering high school with the accurate conceptual understanding of photosynthesis that is needed to grasp the details of the light dependent and light independent reactions of photosynthesis that they are expected to learn in high school. My findings and observations have also resulted in several suggestions for future research and recommendations for the classroom.

7.1. Suggestions for Future Research 1)

Explore students’ understanding about photosynthesis, chloroplasts, and

chlorophyll by asking additional questions. Do students understand the relationship between photosynthesis, chlorophyll, and chloroplasts? 2)

Explore students’ understanding about the flow of matter and energy

through photosynthesis and cellular respiration using additional and refined questions. Does the wording of “cellular respiration” and “respiration” affect students’ responses? Do students understand how plants get their energy during germination and growth? 3)

Quantify and explore the correlation between teacher pedagogical content

knowledge and students’ gains in understanding by asking teachers to predict their students’ responses using percentages. 4)

Do teachers have an accurate conceptual understanding about

photosynthesis? Identify gaps in teacher content knowledge about photosynthesis by asking teachers to answer the photosynthesis concept survey.

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7.2. Recommendations for the Classroom 1)

Use a variety of plants and animals when teaching photosynthesis (i.e.

non-green plants, plants without leaves, sea slugs). Avoid the misconception that photosynthesis only occurs in the leaves by avoiding figures that emphasize the leaves. An ideal figure would include several arrows involving different parts of the plant that photosynthesize. 2)

Involve as much student interaction as possible via inquiry-based

activities, student discussions, and concept mapping (Amir and Tamir 1994; Novak 1995; National Research Council 2000; Carr 2001; Brown 2003; Thompson 2007; O’Connell 2008; Ray and Beardsley 2008). 3)

Identify gaps in students’ conceptual understanding about photosynthesis

using the revised survey in Appendix H to guide instruction. Be sure high school students have the necessary conceptual base before delving into the details of photosynthesis. 4)

Identify any gaps in the teacher’s understanding about photosynthesis.

Use the teacher notes in Appendix H to understand what the common student misconceptions are about photosynthesis.

Though the scope of my study was small (335 students; 9 teachers), and participants were self-selected, my study suggests that there are gaps in students’ conceptual understanding about photosynthesis throughout middle and high school. These gaps in understanding about the connection between chlorophyll and photosynthesis, the energy source for photosynthesis, the source of biomass in plants, and

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the connection between cellular respiration and photosynthesis in plants must be addressed in the classroom. Teachers are encouraged to use the revised survey in Appendix H to assess their students’ prior knowledge about photosynthesis in order to shape their lessons. Assessing prior knowledge is especially important in high school, where students may not be coming in with an accurate conceptual understanding of photosynthesis that is necessary to learn the details. My study raises many questions yet to be answered regarding student learning about photosynthesis. Because it is an important concept, the life-science education community must keep working together to improve students’ understanding about photosynthesis so that students become informed citizens as adults.

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Marmaroti, P., Galanopoulou, D. (2006). "Pupils' understanding of photosynthesis: A questionnaire for the simultaneous assessment of all aspects." International Journal of Science Education 28 (4): 383-403. Maxwell, A. E. (1970). "Comparing the classification of subjects by two independent judges." British Journal of Psychiatry 116: 651-655. Merriam-Webster Online Visual Dictionary, http://visual.merriam-webster.com/plantsgardening/plants/plant/photosynthesis.php, Accessed July 2010. Miller, K., and Levine, J. (2010). Biology. One Lake Street, Upper Saddle River, NJ. Pearson Education Inc. National Committee on Science Education Standards and Assessment, N. R. C. (1996). National Science Education Standards. Washington, DC, National Academy Press. National Research Council (2000). "Inquiry and the national science education standards." Washington, DC: National Academy Press. Nilsson, P. (2008). "Teaching for Understanding: The complex nature of pedagogical content knowledge in pre-service education." International Journal of Science Education 30 (10): 1281-1299. Novak, J. D. (1995). "Concept mapping to facilitate teaching and learning." Prospects 25 (1): 79-86. Novick, S., Nussbaum, J. (1981). "Pupils' understanding of the particulate nature of matter: a cross-age study." Science Education 65: 187-196. O'Connell, D. (2008). "Shortcomings of Commonly-Used Exercises on Photosynthesis and Cellular Respiration." The American Biology Teacher 70 (6): 350-356. Osborne, R., Freyberg, P. (1985) "Learning in science." London: Heinemann. Ozay, E., Oztas, H. (2003). "Secondary students' interpretations of photosynthesis and plant nutrition." Journal of Biological Education 37 (2). Ray, A. M., Beardsley, P. M. (2008). "Overcoming Student Misconceptions about Photosynthesis: A Model- and Inquiry-Based Approach Using Aquatic Plants." Science Activities 45 (1): 13-22. Rice, D. C. (2005). "I didn't know oxygen could boil! What preservice and inservice elementary teachers' answers to "simple" science questions reveals about their subject matter knowledge." International Journal of Science Education 27 (9): 1059-1082. 90

Ross, P., Tronson, D., Ritchie, R. J. (2005). "Modelling Photoysnthesis to Increase Conceptual Understanding." Journal of Biological Education 40 (2): 84-88. Rumpho, M.E., Worful, J.M., Lee, J., Kannan, K., Tyler M.S., Bhattacharya, D., Moustafa, A., Manhart, J.R. (2008). "Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica." Proceedings of the National Academy of Sciences USA. 105:17867-17871 Seymore, J., Longden, B. (1991). "Respiration, that's breathing isn't it?" Journal of Biological Education 25 (3): 177-183. Shulman, L. S. (1986). "Those who understand teach: knowledge growth in teaching." Educational Researcher 15 (2): 4-14. Simpson, M. A., Arnold, B. (1982). "The inappropriate use of subsumers in biology learning." European journal of science education 4: 173-183. Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, M., Tignor and H.L. Miller (eds). (2007). "Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007." Cambrige University Press. Cambride, United Kingdom and New York, NY, USA. Songer, C., Mintzes, J. (1994). "Understanding cellular respiration and analysis of conceptual change in college biology." Journal of Research in Science Teaching 31 (6): 637. Stavy, R., Yehudit, Yaakobi, Duba (1987). "How students aged 13-15 understand photosynthesis." International Journal of Science Education 9 (1): 105-115. Stavy, R. (1990). "Children's conceptions of changes in the state of matter: from liquid (or solid) to gas." Journal of Research of Science Teaching 27: 247-266. Stuart, A. (1955). "A test for homogeneity of the arginal distributions in a two-way classification." Biometrika 42 (3/4): 412-416. Thompson, S. L. (2007). "The Plant-in-a-Jar as a Catalyst for Learning." Science Activities 43 (4): 27-33. van Driel, J. H., Verloop, N., de Vos, W. (1998). "Developing Science Teachers' Pedagogical Content Knowledge." Journal of Research in Science Teaching 35 (6): 673-695. Waheed, T. L., Lucas, A. M. (1992). "Understanding interrelated topics: photosynthesis at age 14+." Journal of Biological Education 26 (3): 193-199.

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APPENDIX A: TEACHER INVITATION LETTER To Whom It May Concern: I am a graduate student in the Master’s of Science in Teaching program at the University of Maine. I am studying students’ understanding of photosynthesis investigating what misconceptions students have as well as what teachers find difficult to teach. I am looking for middle and high school biology classes to take a brief pre- and postsurvey before and after your photosynthesis unit. Your participation would help me identify what misconceptions students in middle and high school have about photosynthesis, and how they might be addressed. If you choose to participate there will be a pre- and post-survey for you and your students to take. Each survey will take between 10-15 minutes, and can be taken online using Survey Monkey. Your participation would be greatly appreciated. If you are interested in participating or would like more information about my study please feel free to contact me. Be sure to leave your name, contact e-mail/phone number, what grade/class you teach, and when you plan to teach photosynthesis. Thank you for your time. -Katie Clegg MST Student **Feel free to forward this e-mail to anyone you think may be interested in participating in my study.

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APPENDIX B: STUDENT PRE- AND POST-SURVEY Survey Monkey Link Pre-Survey: http://www.surveymonkey.com/s.aspx?sm=cxAfdd_2bfifcxY3_2fzC7L_2bFQ_3d_3d Survey Monkey Link Post-Survey: http://www.surveymonkey.com/s.aspx?sm=HIpNqqx39CYgMRRF3_2fp2VQ_3d_3d Questions: 1. In which part of the plant does photosynthesis take place? A. B. C. D.

Photosynthesis takes place in the roots Photosynthesis takes place in the leaves Photosynthesis takes place in all green parts of the plant Photosynthesis takes place in the whole plant

2. Which part of the plant contains chlorophyll? A. B. C. D.

Chlorophyll is in the roots Chlorophyll is in the leaves Chlorophyll is in the green parts of the plant Chlorophyll is in the whole plant

3. When does photosynthesis take place? A. B. C. D.

Photosynthesis takes place during the day Photosynthesis takes place when there is light Photosynthesis takes place continuously Photosynthesis takes place at night

4. Do plants need light to live and grow? ________________ Explain your reasoning. 5. A bean plant needs energy to survive and grow. Where does that energy come from? (Check all that apply) A. Air B. Water C. Sun D. Soil E. Fertilizer F. All of the above

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6. What effect does photosynthesis have on carbon dioxide in the atmosphere? A. Photosynthesis increases carbon dioxide in the atmosphere B. Photosynthesis decreases carbon dioxide in the atmosphere C. Photosynthesis has no effect on carbon dioxide in the atmosphere Explain your reasoning. 7. Humans engage in respiration; which other living things engage in respiration? (Check all that apply) A. Snail B. Bacteria C. Rose plant D. Cow E. Mushroom F. All of the above 8. Where in the human body does respiration take place? (Check all that apply) A. Muscles B. Stomach C. Lungs D. Skin E. Brain F. All body cells

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APPENDIX C: TEACHER PRE-SURVEY Survey Monkey Link: http://www.surveymonkey.com/s.aspx?sm=gEe3HW7kYIhv4kL2RnxWBQ_3d_3d

Dear ____________________; This pre-survey is to help me learn about how photosynthesis is taught in middle and high schools, and what you, as a teacher find to be most difficult about teaching this topic effectively. 1. How much time do you spend teaching about photosynthesis in your class? 2. Which textbook(s) and/or curriculum materials do you use to teach photosynthesis, if any? 3. What hands-on activities or laboratory exercises do you use to teach photosynthesis? 4. What key concepts or understanding related to photosynthesis do you want your students to learn? 5. What key concepts or understanding related to photosynthesis do you find difficult to get across to your students?

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APPENDIX D: TEACHER POST-SURVEY Survey Monkey Link: http://www.surveymonkey.com/s.aspx?sm=i5uqhTCD6zJ0C39i09jOlg_3d_3d

Dear ___________________; Imagine you were to give your students the following quiz about photosynthesis following your instructional “unit” on photosynthesis. For each of the following 10 questions, please indicate for EACH OPTION, if most, some, or few/none of your students would choose that as THEIR ANSWER. Example question, questions identical to student survey Questions 1, 2, 3, 5, 6, 7, & 8: 1. In which part of the plant does photosynthesis take place? A. B. C. D.

Photosynthesis takes place in the roots Photosynthesis takes place in the leaves Photosynthesis takes place in all green parts of the plant Photosynthesis takes place in the whole plant

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Most ____ ____ ____ ____

Some Few/None ____ ____ ____ ____ ____ ____ ____ ____

APPENDIX E: INSTITUTIONAL REVIEW BOARD FOR THE PROTECTION OF HUMAN SUBJECTS PROTOCOL Summary of the proposal. National and State Education Standards indicate that photosynthesis is a fundamental concept that students at all levels need to understand. However, research shows that it is a very difficult and complex concept for students. I plan to research the following questions about photosynthesis education: What do students at different levels understand and what misconceptions persist through time about photosynthesis? I will administer a written pre-survey to students in 8th grade and high school biology classes before any instruction about photosynthesis to measure the knowledge and misconceptions that students bring to the classroom. Then, after instruction I will give the same students the same post-survey to measure any gains in their knowledge about photosynthesis as well as to see what, if any, misconceptions still persist after instruction. What do teachers find difficult to teach within the photosynthesis unit? At the same time I survey the students I will survey their teacher during both the pre- and post-surveys. The teacher’s pre-survey will include questions about instructional activities, texts, and curricula they use to teach photosynthesis, how long the unit is, what concepts they teach, and what they find particularly difficult to teach about photosynthesis. What do teachers think their students know about photosynthesis? The teacher’s post-survey will mirror the student survey, but with the instructions to answer how they believe their average student would answer the question. The teacher’s answers will be compared to that of their students post-survey. That information will be used to see how knowledgeable teachers are of what their students understand about photosynthesis. The data collected from the surveys will be used to develop a workshop for middle and high school biology teachers with the aim of improving the instruction of photosynthesis. I plan to use survey monkey to administer the surveys online, and will send the teachers the link to the surveys via e-mail.

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Timeline: Instrument

To Whom?

Date

Students

Fall 2008

Written presurvey to teachers

Collect information on student knowledge of photosynthesis and identify possible misconceptions before the photosynthesis unit. Collect information on what materials teachers use, concepts covered, and difficulties they encounter.

Teachers

Fall 2008

Written postsurvey to students Written postsurvey to teachers

Gather information on student learning of photosynthesis concepts after the photosynthesis unit. Find out what concepts teachers think their students understand after instruction.

Students

Fall 2008 or Spring 2009

Teachers

Fall 2008 or Spring 2009

Written presurvey to students

Purpose

Personnel. I, Katie Clegg, and members of my thesis advisory committee: Molly Schauffler, Mary Rumpho, and Susan McKay, will have contact with the data collected. Subject recruitment. I plan to recruit eight middle and high school biology teachers (four each of middle and high school) to participate in the study by sending out an e-mail invitation (via the Maine Science Teachers ListServ as well as to contacts in the local schools) for their class to participate (draft enclosed). For those who do participate I will go into their classrooms and give the teacher and their students the survey. Participation will be entirely voluntary. Informed consent. The surveys will focus on the content understanding of photosynthesis and will be no different from normal classroom activities. Thus, I have not included a consent form for the student surveys. I will provide a consent form for the teachers who participate (draft enclosed). Confidentiality. All responses to the surveys will remain confidential. When the students and teachers they will fill in their name, but it will be immediately removed and coded based on student, classroom, and teacher, and whether it was the pre- or postsurvey. Risks to subjects. There will be no more risk than in everyday living. The surveys will take no longer than 15 minutes. Benefits. The benefit of this research project is to find out what misconceptions about photosynthesis persist over time and instruction, provide teachers with this information, and via the workshop, improve how photosynthesis is taught. The teachers who participate will benefit by learning about what misconceptions their students hold about photosynthesis.

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APPENDIX F: NON-SIGNIFICANT RESULTS FROM THE STUDENT SURVEYS Questions 1 and 2 cross-analysis: 1. In which part of the plant does photosynthesis take place? A. Photosynthesis takes place in the roots B. Photosynthesis takes place in the leaves C. Photosynthesis takes place in all green parts of the plant D. Photosynthesis takes place in the whole plant 2. Which part of the pant contains chlorophyll? A. Chlorophyll is in the roots B. Chlorophyll is in the leaves C. Chlorophyll is in the green parts of the plant D. Chlorophyll is in the whole plant

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Pre-Survey (Q1/Q2)

Post-Survey (Q1/Q2)

Green parts/Green parts

Green parts/Green parts

Leaves/Leaves

Leaves/Leaves

Whole plant/Whole plant

Whole plant/Whole plant

Leaves/Green parts Green parts/Leaves

Leaves/Green parts Green parts/Leaves

Other combination

Other combination

Figure F.1. Q 1 & 2; middle school class M01 (n= 58). Thickness of the line represents the number of students.

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Pre-Survey (Q1/Q2)

Post-Survey (Q1/Q2)

Green parts/Green parts

Green parts/Green parts

Leaves/Leaves

Leaves/Leaves

Whole plant/Whole plant

Whole plant/Whole plant

Leaves/Green parts Green parts/Leaves

Leaves/Green parts Green parts/Leaves

Other combination

Other combination

Figure F.2. Q 1 & 2; middle school class M03 (n = 26). Pre-Survey (Q1/Q2)

Post-Survey (Q1/Q2)

Green parts/Green parts

Green parts/Green parts

Leaves/Leaves

Leaves/Leaves

Whole plant/Whole plant

Whole plant/Whole plant

Leaves/Green parts Green parts/Leaves

Leaves/Green parts Green parts/Leaves

Other combination

Other combination

Figure F.3. Q 1 & 2; high school basic biology class H04 (n = 18).

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Pre-Survey (Q1/Q2)

Post-Survey (Q1/Q2)

Green parts/Green parts

Green parts/Green parts

Leaves/Leaves

Leaves/Leaves

Whole plant/Whole plant

Whole plant/Whole plant

Leaves/Green parts Green parts/Leaves

Leaves/Green parts Green parts/Leaves

Other combination

Other combination

Figure F.4. Q 1 & 2; high school basic biology class H08 (n = 12). Pre-Survey (Q1/Q2)

Post-Survey (Q1/Q2)

Green parts/Green parts

Green parts/Green parts

Leaves/Leaves

Leaves/Leaves

Whole plant/Whole plant

Whole plant/Whole plant

Leaves/Green parts Green parts/Leaves

Leaves/Green parts Green parts/Leaves

Other combination

Other combination

Figure F.5. Q 1 & 2; high school advanced biology class H08 (n = 7).

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Question 3: When does photosynthesis take place? A. B. C. D.

Photosynthesis takes place during the day Photosynthesis takes place when there is light Photosynthesis takes place continuously Photosynthesis takes place at night

Class M01 n = 59 = 0.29

Class M04 n = 41 = -0.10

Class M06 n = 77 = -0.10

Figure F.6. Q 3; middle school classes M01, M04, and M06. Pre-survey (black bars), post-survey (grey bars), normalized gain (), number of students (n), correct answer (*).

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Class H04 n = 18 = -1.70

Class H08 n = 12 = -0.60

Figure F.7. Q 3; high school basic biology classes H04 and H08.

Class H02 n = 10 = -0.70

Class H07 n = 27 = 0.13

Class H08 n=7 = -0.50

Figure F.8. Q 3; high school advanced biology classes H02, H07, and H08.

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Question 4: Do plants need light to live and grow? ________________ Explain your reasoning.

Class M01 n = 64 = 0.22

Class M03 n = 27 = 0.17

Figure F.9. Q 4; middle school classes M01 and M03. Pre-survey (black bars), postsurvey (grey bars), normalized gain (), number of students (n), correct answer (*).

Class H04 n = 18 = 0.08

Class H08 n = 12 = -0.33

Figure F.10. Q 4; high school basic biology classes H04 and H08.

106

Class H02 n = 10 = 0

Class H07 n = 25 = 0.50

Class H08 n=7 = 1.00

Figure F.11. Q 4; high school advanced biology classes H02, H07, and H08.

107

Question 5: A bean plant needs energy to survive and grow. Where does that energy come from? (Check all that apply) A. Air B. Water C. Sun D. Soil E. Fertilizer F. All of the above

Class M01 n = 58 = 0.02

Class M03 n = 27 = -0.10

Class M04 n = 41 = -0.03

Figure F.12. Q 5; middle school classes M01, M03, and M04. Pre-survey (black bars), post-survey (grey bars), normalized gain (), number of students (n), correct answer (*).

108

Class H04 n = 18 = 0

Class H08 n = 12 = 0

Figure F.13. Q 5; high school basic biology classes H04 and H08.

Class H02 n = 10 0

Class H08 n=7 = 0

Figure F.14. Q 5; high school advanced biology classes H02 and H08.

109

Question 6a: What effect does photosynthesis have on carbon dioxide in the atmosphere? A. Photosynthesis increases carbon dioxide in the atmosphere B. Photosynthesis decreases carbon dioxide in the atmosphere C. Photosynthesis has no effect on carbon dioxide in the atmosphere

Class M01 n = 59 = 0.06

Class M03 n = 27 = 0

Class M04 n = 41 = 0

Class M05 n = 75 = 0.17

Figure F.15. Q 6a; middle school classes M01, M03, M04, and M05. Pre-survey (black bars), post-survey (grey bars), normalized gain (), number of students (n), correct answer (*).

110

Class H08 n = 12 = 0

Figure F.16. Q 6a; high school basic biology class H08.

Class H02 n = 10 = 1.00

Class H08 n=7 = 0

Figure F.17. Q 6a; high school advanced biology classes H02 and H08.

111

Question 6b: Explain your reasoning.

Class M01 n = 59 = 0.25

Class M03 n = 27 = 0.17

Figure F.18. Q 6b; middle school classes M01 and M03. Pre-survey (black bars), postsurvey (grey bars), normalized gain (), number of students (n), correct answer (*). Class H04 n = 18 = -0.09

Class H08 n = 12 = 0

Figure F.19. Q 6b; high school basic biology classes H04 and H08.

112

Class H02 n = 10 = 0

Class H07 n = 25 = 0.40

Class H08 n=7 = 0

Figure F.20. Q 6b; high school advanced biology classes H02, H07, and H08.

113

Question 7: Humans engage in respiration; which other living things engage in respiration? (Check all that apply) A. Snail B. Bacteria C. Rose plant D. Cow E. Mushroom F. All of the above Class M01 n = 59 = -0.16

Class M03 n = 27 = -0.11

Class M05 n = 75 = 0.17

Class M06 n = 77 = 0.18

Figure F.21. Q 7; middle school classes M01, M03, M05, and M06. Pre-survey (black bars), post-survey (grey bars), normalized gain (), number of students (n), correct answer (*).

114

Class H04 n = 18 = -0.83

Class H08 n = 12 = 0.20

Figure F.22. Q 7; high school basic biology classes H04 and H08. Class H02 n = 10 = 0

Class H08 n=7 = 0

Figure F.23. Q 7; high school advanced biology classes H02 and H08.

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Question 8: Where in the human body does respiration take place? (Check all that apply) A. Muscles B. Stomach C. Lungs D. Skin E. Brain F. All body cells

Class M01 n = 59 = -0.06

Class M03 n = 27 = 0.27

Class M04 n = 41 = -0.28

Class M06 n = 77 = 0.07

Figure F.24. Q 8; middle school classes M01, M03, M04, and M06. Pre-survey (black bars), post-survey (grey bars), normalized gain (), number of students (n), correct answer (*).

116

Class H04 n = 18 = 0.20

Class H08 n = 12 = -5.00

Figure F.25. Q 8; high school basic biology classes H04 and H08.

Class H02 n = 10 = 0.33

Class H07 n = 25 = -0.20

Class H08 n=7 = 0

Figure F.26. Q 8; high school advanced biology classes H02, H07, and H08.

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APPENDIX G: TEACHERS’ PREDICTIONS OF STUDENTS’ POST-SURVEY RESPONSES

Middle school teacher M01 Question 1

A

B

C*

D

% of students Prediction

4

33

15

48

Few/None

Most

Some

Few/None

Question 2

A

B

C*

D

% of students Prediction

5

47

41

7

Few/None

No response

Some

Some

Question 3

A

B*

C

D

% of students Prediction

7

66

25

2

Most

Some

Few/None

Few/None

Question 5

A

B

C*

D

E

F

% of students Prediction

2

2

10

0

2

41

Some

Few/None

Most

Few/None

Few/None

Some

Question 6

A

B*

C

% of students Prediction

15

73

12

Few/None

Most

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

3

2

2

3

2

51

Most

Some

Few/None

Most

Some

Some

Question 8

A

B

C

D

E

F*

% of students Prediction

0

5

34

7

0

41

Some

Few/None

Most

Some

Some

Some

Table G.1. Middle school teacher M01; teacher post-survey predictions compared to actual students’ responses on the student post-survey. Correct answer (*), over predictions (dark grey), under predictions (light grey), matched predictions (white). 118

Middle school teacher M03 Question 1

A

B

C*

D

% of students Prediction

4

48

15

33

Few/None

Most

Most

Some

Question 2

A

B

C*

D

% of students Prediction

0

56

33

11

Few/None

Most

Most

Some

Question 3

A

B*

C

D

% of students Prediction

30

48

22

0

Most

Most

Some

Few/None

Question 5

A

B

C*

D

E

F

% of students Prediction

0

0

19

4

0

48

Some

Some

Most

Some

Some

Some

Question 6

A

B*

C

% of students Prediction

11

59

30

Most

Few/None

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

0

7

0

0

7

26

Some

Few/None

Some

Most

Some

No response

Question 8

A

B

C

D

E

F*

% of students Prediction

0

0

30

7

0

59

Most

Most

Most

Most

Most

Most

Table G.2. Middle school teacher M03; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

119

Middle school teacher M04 Question 1

A

B

C*

D

% of students Prediction

0

93

3

5

Some

Most

Most

Some

Question 2

A

B

C*

D

% of students Prediction

7

41

41

10

Some

Most

Most

Some

Question 3

A

B*

C

D

% of students Prediction

27

49

22

2

Most

Most

Some

Few/None

Question 5

A

B

C*

D

E

F

% of students Prediction

0

0

5

0

0

59

Some

Most

Most

Most

Some

Most

Question 6

A

B*

C

% of students Prediction

27

66

7

Few/None

Most

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

0

2

2

7

2

49

Some

Some

Some

Most

Some

Some

Question 8

A

B

C

D

E

F*

% of students Prediction

2

2

3

2

0

44

Some

Some

Most

Some

No response

Some

Table G.3. Middle school teacher M04; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

120

Middle school teacher M05 Question 1

A

B

C*

D

% of students Prediction

1

26

61

12

Few/None

Some

Most

Few/None

Question 2

A

B

C*

D

% of students Prediction

1

43

47

8

Few/None

Some

Most

Few/None

Question 3

A

B*

C

D

% of students Prediction

47

51

1

1

Most

Some

Some

Some

Question 5

A

B

C*

D

E

F

% of students Prediction

1

0

7

0

0

27

Some

Some

Some

Few/None

Few/None

Most

Question 6

A

B*

C

% of students Prediction

13

67

20

Some

Most

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

0

3

1

4

1

33

Few/None

Few/None

Few/None

Some

Few/None

Most

Question 8

A

B

C

D

E

F*

% of students Prediction

5

0

15

1

0

59

Few/None

Few/None

Few/None

Few/None

Some

Most

Table G.4. Middle school teacher M05; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

121

Middle school teacher M06 Question 1

A

B

C*

D

% of students Prediction

0

57

19

23

Some

Most

Most

Most

Question 2

A

B

C*

D

% of students Prediction

0

1

42

57

Some

Most

Most

Most

Question 3

A

B*

C

D

% of students Prediction

5

61

32

1

Most

Most

Few/None

Few/None

Question 5

A

B

C*

D

E

F

% of students Prediction

1

1

21

1

0

23

Some

Some

Most

No response

No response

No response

Question 6

A

B*

C

% of students Prediction

23

70

6

Some

Some

Some

Question 7

A

B

C

D

E

F*

% of students Prediction

3

0

1

5

0

57

No response

No response

No response

No response

No response

Most

Question 8

A

B

C

D

E

F*

% of students Prediction

3

4

38

6

3

34

Few/None

Few/None

Most

Few/None

Few/None

Some

Table G.5. Middle school teacher M06; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

122

High school teacher H02 Question 1

A

B

C*

D

% of students Prediction

0

30

60

10

Few/None

Most

Some

Few/None

Question 2

A

B

C*

D

% of students Prediction

0

20

70

10

Few/None

Most

Some

Few/None

Question 3

A

B*

C

D

% of students Prediction

0

50

50

0

Some

Most

Few/None

0

Question 5

A

B

C*

D

E

F

% of students Prediction

0

0

10

0

0

60

Few/None

Few/None

Most

Few/None

Few/None

Few/None

Question 6

A

B*

C

% of students Prediction

0

100

0

Few/None

Most

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

0

0

0

10

0

60

Few/None

Most

Most

Most

Most

Most

Question 8

A

B

C

D

E

F*

% of students Prediction

10

0

20

0

0

60

Most

Most

Most

Most

Most

Most

Table G.6. High school teacher H02; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

123

High school teacher H04 Question 1

A

B

C*

D

% of students Prediction

6

50

33

11

Few/None

Most

Some

Some

Question 2

A

B

C*

D

% of students Prediction

0

39

56

6

Few/None

Most

Most

Some

Question 3

A

B*

C

D

% of students Prediction

11

56

22

11

Some

Most

Some

Few/None

Question 5

A

B

C*

D

E

F

% of students Prediction

0

0

11

6

0

61

Few/None

Some

Most

Few/None

Some

Some

Question 6

A

B*

C

% of students Prediction

33

61

6

Few/None

Most

Some

Question 7

A

B

C

D

E

F*

% of students Prediction

0

11

6

6

6

39

No response

Most

Some

Some

Most

Some

Question 8

A

B

C

D

E

F*

% of students Prediction

6

0

33

0

6

56

Some

Most

Most

Most

Most

Most

Table G.7. High school teacher H04; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

124

High school teacher H07 Question 1

A

B

C*

D

% of students Prediction

0

84

16

0

Few/None

Most

Most

Some

Question 2

A

B

C*

D

% of students Prediction

0

0

44

56

Few/None

Most

Most

Some

Question 3

A

B*

C

D

% of students Prediction

12

72

16

0

Most

Most

Some

Few/None

Question 5

A

B

C*

D

E

F

% of students Prediction

0

0

60

0

0

32

Some

Some

Most

Few/None

Few/None

Few/None

Question 6

A

B*

C

% of students Prediction

8

76

16

Some

Most

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

0

0

0

0

0

60

Most

Some

Most

Most

Most

Some

Question 8

A

B

C

D

E

F*

% of students Prediction

0

0

20

0

0

76

Some

Some

Some

Some

Most

Most

Table G.8. High school teacher H07; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

125

High school teacher H08 Question 1

A

B

C*

D

% of students Prediction

0

37

21

42

Few/None

Most

Most

Some

Question 2

A

B

C*

D

% of students Prediction

0

37

47

16

Few/None

Most

Most

Some

Question 3

A

B*

C

D

% of students Prediction

11

42

47

0

Most

Most

Some

Some

Question 5

A

B

C*

D

E

F

% of students Prediction

0

0

11

0

5

58

Few/None

Some

Most

Few/None

Few/None

Few/None

Question 6

A

B*

C

% of students Prediction

21

79

0

Few/None

Most

Few/None

Question 7

A

B

C

D

E

F*

% of students Prediction

0

0

0

11

0

53

Few/None

Few/None

Some

Few/None

Some

Most

Question 8

A

B

C

D

E

F*

% of students Prediction

11

0

16

5

0

63

Some

Few/None

Most

Few/None

Few/None

Some

Table G.9. High school teacher H08; teacher post-survey predictions compared to actual students’ responses on the student post-survey.

126

Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match X

Over

Under

X X X X X X X X

0.20 0.17 0.90 0.70 0.54 0.67 0.57 1.00 -0.24

Table G.10. Q 1; teachers’ predictions compared to their class’s normalized gains (). Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match X

Over

Under

X X X X X X X X

0.50 0.70 0.46 0.65 0.94 -10 0.80 1.00 -5

Table G.11. Q 2; teachers’ predictions compared to their classes’ normalized gains. Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match

Over

Under X

X X X X X X X X

0.29 -0.17 -0.10 -0.16 -0.10 -0.70 -1.70 0.13 -0.55

Table G.12. Q 3; teachers’ predictions compared to their classes’ normalized gains. Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match

Over X X X X X X X

X X

Under

0.02 -0.01 -0.03 -0.11 0.16 0 0 0.58 0

Table G.13. Q 5; teachers’ predictions compared to their classes’ normalized gains.

127

Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match X

Over

Under X

X X X X X X X

0.06 0 0 0.17 0.41 1.00 0 0.14 0

Table G.14. Q 6a; teachers’ predictions compared to their classes’ normalized gains. Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match

Over

Under X

No response X X X X X X X

-0.16 -0.11 0.13 0.17 0.18 0 -0.83 -0.67 0.10

Table G.15. Q 7; teachers’ predictions compared to their classes’ normalized gains.

Teacher M01 M03 M04 M05 M06 H02 H04 H07 H08

Match

Over

Under X

X X X X X X X X

-0.06 0.27 -0.28 0.39 0.07 0.33 0.20 -0.20 -2.5

Table G.16. Q 8; teachers’ predictions compared to their classes’ normalized gains.

128

APPENDIX H: REVISED STUDENT SURVEY FOR CLASSROOM USE For teachers to use to assess students’ understanding prior to instruction about photosynthesis 1. Choose the best answer to the following questions: a) Where in plants does photosynthesis take place? ____ the roots ____ the leaves ____ all green parts ____ the whole plant

b) Where in plants is c) Where in plants are chlorophyll located? chloroplasts located? _____ the roots _____ the roots _____ the leaves _____ the leaves _____ all green parts _____ all green parts _____ the whole plant _____ the whole plant

Explain your reasoning. 2. When does photosynthesis take place? (Choose the best answer) A. B. C. D.

Photosynthesis takes place only during the day Photosynthesis takes place when there is light Photosynthesis takes place continuously Photosynthesis takes place at night

3. Do plants need light to live and grow? ________________ Why or why not? 4. A bean plant needs energy for photosynthesis. Where does that energy come from? (Check all that apply) A. Air B. Water C. Sun D. Soil E. Fertilizer F. All of the above 5. Which of the following processes occurs in a seed during germination? A. Photosynthesis B. Cellular Respiration C. Both D. Neither Explain your reasoning.

129

6. What effect does photosynthesis have on carbon dioxide in the atmosphere? A. Photosynthesis increases carbon dioxide in the atmosphere B. Photosynthesis decreases carbon dioxide in the atmosphere C. Photosynthesis has no effect on carbon dioxide in the atmosphere Explain your reasoning. 7. A plant’s body mass is made up of carbon-based molecules. Where does that carbon come from? A. Air B. Water C. Sun D. Soil E. Fertilizer F. All of the above Explain your reasoning. 8. Humans engage in cellular respiration; which other living things engage in cellular respiration? (Check all that apply) A. Snail B. Bacteria C. Rose plant D. Cow E. Mushroom F. All of the above 9. Where in the human body does cellular respiration take place? (Check all that apply) A. Muscles B. Stomach C. Lungs D. Skin E. Brain F. All body cells

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NOTES FOR TEACHERS: 1.

Correct Answers: a) All green parts, b) All green parts, c) All green parts Correct Explanation: Photosynthesis occurs within any cell that contains chlorophyll. Common Misconception: The most common misconception related to chlorophyll, chloroplasts, and photosynthesis is that it only occurs in the leaves. This misconception may stem from the figures used to teach photosynthesis that emphasize only the leaves of the plant. If a student chooses “leaves” for all three questions, it suggests that the student does understand the connection between chlorophyll, chloroplasts, and photosynthesis. However, the student does not seem to understand that chlorophyll is green, therefore, any green part of the plant will photosynthesize. How a student answers each question can provide clues to what that student thinks about chlorophyll, chloroplasts, and photosynthesis. For example, if a student picks a different answer for each question, they probably do not understand the connection between chlorophyll, chloroplasts, and photosynthesis. If a student chooses the same answers for questions 1 and 2, the student seems to understand that chlorophyll is necessary for photosynthesis. If a student chooses the same answer for questions 1 and 3, the student understands that chloroplasts are necessary for photosynthesis. If a student chooses the same answer for questions 2 and 3, the student understands the connection between chlorophyll and chloroplasts.

2.

Correct Answer: B, Photosynthesis takes place when there is light. Any time light (natural or artificial) is present and plant will undergo photosynthesis. Common Misconception: A, Photosynthesis takes place during the day. Students may have the misconception that plants photosynthesize only during the daytime, they may not take into account artificial light.

3.

Correct Answer: Yes, plants need light to live and grow because they undergo photosynthesis, and in order for photosynthesis to occur, there needs to be light present. Common Misconception: Students may think that plants only need soil, air, water, fertilizer, or a combination of these. They may not connect light with photosynthesis.

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4.

Correct Answer: C, sun only. A plant’s only energy source for photosynthesis is the sun. Common Misconception: The most common misconception regarding the energy source for photosynthesis is that a plant’s energy comes from multiple sources such as air, water, soil, and fertilizer.

5.

Correct Answer: B, cellular respiration because plants use the energy stored within the sugars of the seed to germinate and grow until it reaches the surface, at which point photosynthesis takes over and the plant begins to increase in mass. Common Misconception: Students most commonly connect photosynthesis to plant growth and may not take into account that there is no sunlight underground, so plants must use an alternative energy source during germination.

6.

Correct Answer: B, Photosynthesis decreases carbon dioxide in the atmosphere because plants use carbon dioxide from the atmosphere during photosynthesis Common Misconception: C, Photosynthesis has no effect on carbon dioxide in the atmosphere because plants use carbon from some other source during photosynthesis. The most common misconception is that plants use carbon in organic matter from the soil during photosynthesis.

7.

Correct Answer: A, air. Plants use carbon dioxide from the atmosphere during photosynthesis to produce sugars that are then incorporated into its’ body mass. Common Misconception: D, soil. Students may believe that plants use carbon in organic matter in the soil during photosynthesis.

8.

Correct Answer: F, All of the above. All organisms, including plants, undergo cellular respiration. Common Misconception: A, Snail and D, Cow. The most common misconception about what types of organisms undergo cellular respiration is that only animals undergo cellular respiration.

9.

Correct Answer: F, All body cells. Cellular respiration occurs at the cellular level in all cells. Common Misconception: C, Lungs. The most common misconception about the location of cellular respiration is that it only occurs within the cells of lungs. Students are connecting cellular respiration to the act of breathing in animals.

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BIOGRAPHY OF THE AUTHOR Katie Clegg was born in Biddeford, Maine. She graduated from Biddeford High School in Biddeford in 2003. From there she entered the University of Maine studying Physical Marine Science. She worked for three years as a laboratory assistant in a biochemistry laboratory sequencing DNA from Antarctic Yeasts. In 2006, Katie was granted a National Science Foundation Research Experience for Undergraduates, in which she spent a summer at the University of Rhode Island performing research in paleoclimatology. In 2007 she graduated from the University of Maine with a Bachelor of Science in Physical Marine Science. After spending the last three years in research and tutoring chemistry, she found that her passion was in teaching. It was the Fall 2007 that she enrolled in the Master of Science in Teaching program at the University of Maine. Katie has received her teaching certification from the State of Maine in physical and life sciences and the State of New Hampshire in physical science. She is now teaching Physics, Chemistry, and Physical Science in Milton, New Hampshire and residing in Sanford, Maine. She is a candidate for the Masters of Science in Teaching degree from the University of Maine in December 2011.

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