UNDERSTANDING WEATHER: PHASE CHANGES OF WATER IN THE ATMOSPHERE

By Elliot D. Rappaport B.A. Oberlin College, 1986

A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science (in Teaching) December, 2007

Advisory Committee Kirk A. Maasch, Professor of Earth Sciences, Advisor Stephen A. Norton, Professor of Earth Sciences John R. Thompson, Assistant Professor of Physics, Cooperating Assistant Professor of Education

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 purposes 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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UNDERSTANDING WEATHER: PHASE CHANGES OF WATER IN THE ATMOSPHERE

By Elliot D. Rappaport Thesis Advisor: Dr. Kirk Maasch

An Abstract for the Thesis Presented In Partial Fulfillment of the Requirements for the Degree of Master of Science (in Teaching) September 2007

This investigation explored the understanding of phase changes of water in the atmosphere among college undergraduates. The study began with a series of interviews with six earth science students at the University of Maine, during which questions were posed regarding the formation and composition of clouds. An analysis of interview results indicated that many students had difficulty with the correct identification of water in its different states, and were unable to identify the sources of moisture in certain cases of cloud formation. Multiple-choice surveys were developed from the interview results, and distributed as pre/post tests to different sections of an introductory geology class at the University. Identical surveys were also given as pre-assessments to participants in “Sea Semester”, a prominent scientific field study program at Woods Hole, Massachusetts. Statistical testing of scores indicated a uniformly low level of initial literacy in the focus topic, among all samples. At the University of Maine, post-test scores indicated that students

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who received inquiry-based thought problems as a supplement to lecture instruction experienced a scoring advantage of approximately six percentile points. The results of this study show a measurable increase in effect where inquiry-based tools are employed in teaching atmospheric concepts, and further development and testing of such materials is recommended. Furthermore, the strong cognitive ties noted between atmospheric processes and the fundamental principles of phase change suggest that an integrated educational approach to these topics might lead to more durable and accurate understanding on the part of students.

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ACKNOWLEDGEMENTS

I thank the University of Maine Center for Science and Mathematics Education Research, and The Graduate School, for funding this research, and my return to school as a whole. Thank you to Susan McKay, for believing that an old sailor had the makings of a new science teacher, and to Carol Bennatti, for allowing me to see what the inside of a high school science classroom really looks like. Thanks also to the University of Maine faculty, specifically Kirk Maasch, Andy Reeve, and Alice Kelley, who provided the class time and support necessary to make this study possible. Kudos to the students, too numerous to name, who soldiered through hundreds of interviews and surveys, offered forth on vague pretenses. It’s fair to say that little I’ve done in my adult life has been accomplished without some support from my long-time friends and colleagues at the Sea Education Association of Woods Hole, Massachusetts, and this project was no exception. Thank you Chuck, Kara, EZ, and all of your students. To my committee, thank you for all you’ve done, and for your willingness to let me wander so far down a path of my own making. I hope that it has proven worthwhile. Finally, thank you to Karen, for demonstrating that anything is possible.

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS……………………………………………………ii LIST OF TABLES……………………………………………………………………... vi LIST OF FIGURES……………………………………………………………………. vii

CHAPTER 1. An Introduction to Educational Questions Regarding the Water Cycle…………… 1 2. Student Understanding of the Water Cycle: A Review of the Literature………….. 7 2.1. Abstract………………………………………………………………………. 8 2.2. Introduction…………………………………………………………………... 9 2.3. Meteorological Misconceptions………………………………………............ 10 2.4. Approaches to Instruction……………………………………………………. 13 2.5. A Systems-Based Model of Instruction……………………………………… 15 2.6. Earth Systems and Visual Representation…………………………………… 16 2.7. Integrating Material Over the Educational Timeline………………………… 17 2.8. Conclusions…………………………………………………………………... 17 3. Interviews With Earth Science Undergraduates Regarding Models for Cloud Formation………………………………………………………. 19 3.1. Abstract………………………………………………………………………. 20 3.2. Introduction…………………………………………………………………... 20

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3.3. Materials and Methods……………………………………………………….. 23 3.3.1. The Interview Classroom……………………………………………. 23 3.3.2. Interview Questions………………………………………………….. 23 3.4. Results and Discussions……………………………………………………… 27 3.5. Conclusions…………………………………………………………………... 39 4. Condensation in the Atmosphere: A Quantitative Survey of Water Literacy Before and After Instruction……………………………………………………….. 41 4.1. Abstract………………………………………………………………………. 42 4.2. Introduction…………………………………………………………………... 42 4.3. Materials and Methods……………………………………………………….. 45 4.3.1. The Survey…………………………………………………………… 45 4.3.2. MCMR Question Design…………………………………………….. 46 4.3.3. Open Response Questions…………………………………………….49 4.3.4. Survey Sample Groups………………………………………………. 50 4.4. Results………………………………………………………………………... 52 4.4.1. MCMR Questions……………………………………………………. 52 4.4.2. Open response Questions…………………………………………….. 61 4.5. Discussions…………………………………………………………………... 61 4.5.1. Analysis of MCMR Pre- and Post-Test Questions…………………... 61 4.5.2. Open Response Questions…………………………………………….63 4.6. Conclusions…………………………………………………………………... 65 5. Implications for Future Research…………………………………………………... 67

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BIBLIOGRAPHY……………………………………………………………………… 70 APPENDICES…………………………………………………………………………. xx Appendix A. The Water Cycle: A Survey………………………………………….. 73 Appendix B. Statistical Test Data for Surveys……………………………………... 75 Appendix C. ERS 102 Score Distributions…………………………………………. 82 Appendix D. Evaporation and Condensation: A Tutorial…………………………... 89 BIOGRAPHY OF THE AUTHOR……………………………………………………. 93

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LIST OF TABLES

Table B.1. A one-way ANOVA of total pre-test scores……………………………… 75 Table B.2. Dependent samples t-tests of ERS 102 pre/post test data………………… 76 Table C.1. ERS 102 survey score distributions………………………………………. 83

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LIST OF FIGURES

Figure 1.1. The water cycle……………………………………………………………xx Figure 4.1. Mean total pre-test scores for all samples in this study…………………... xx Figure 4.2. Mean total pre- and post-test scores for ERS 102 students………………. xx Figure 4.3. Question 1 mean pre- and post-test scores for ERS 102 students………... xx Figure 4.4. Question 2 mean pre and post-test scores for ERS 102 students………… xx Figure 4.5. Question 3 mean pre- and post-test scores for ERS 102 students………... xx Figure 4.6. Question 4 mean pre- and post-test scores for ERS 102 students………... xx Figure 4.7. Question 5 mean pre- and post-test scores for ERS 102 students………... xx

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Chapter 1: An Introduction to Educational Issues Regarding the Water Cycle

Clouds and precipitation are visible manifestations of the transition of water between its solid, liquid, and vaporous (gaseous) phases in the atmosphere. These changes are primary mechanisms for the atmospheric distribution of moisture and heat energy, and central to most meteorological phenomena. The complete “water cycle”, with the added terrestrial components of deposition, storage, and runoff, is a major driver of geological and climatic systems, and a cornerstone of the biosphere (Fig. 1.1.).

transport condensation & deposition precipitation

precipitation sublimation evaporation

runoff

The Water Cycle

Fig. 1.1. The water cycle, showing the fundamental stages of evaporation, sublimation, transport, condensation, deposition, precipitation, and runoff. (Murphy, J., 2005.) 1

The physical principles that underlie the water cycle are well addressed in educational standards, and governed by some of the most basic relationships between matter and energy. The Maine Learning Results (MLR), an evolving set of state standards for precollege science education, speak explicitly to issues regarding phase change and the water cycle, stating that, by graduation from high school, students shall: ƒ Understand the structure of matter, and the changes it can undergo. ƒ Illustrate the cycles of matter in the environment, and explain their relationship. ƒ Analyze how matter is affected by changes in temperature, pressure, and volume. ƒ Describe how energy put into or taken out of a system can cause changes in the motion of particles in matter. ƒ Explain the relationship between temperature, heat, and molecular motion. ƒ Study weather fronts as well as short-term catastrophic events (e.g. hurricanes and tornadoes) ƒ Describe how air pressure, temperature, and moisture interact to cause changes in the weather. ƒ Measure physical changes in the atmosphere to predict the weather.

If followed successfully, these criteria suggest that students should arrive at college with at least a qualitative view of how atmospheric processes work, and a grasp of how earth systems are connected to the physical principles that govern them. Pursuant to standards like the MLR, college instructors assume that their students have been exposed, at least qualitatively, to the concepts of heat and temperature, molecular kinetics, and the primary states of matter.

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Aside from formal instruction, college students possess, literally, a lifetime of observational experience with the water cycle. They have all seen kettles boiling, bathtubs steaming, and the slow accumulation of clouds before a rainstorm. Many have noticed the coincidence of temperature change and precipitation, and the connection that often exists between wind, clouds, and weather events. To the alert instructor, this suite of common examples represents a windfall of opportunities. Any classroom with a window and a thermometer may become a laboratory for the discussion of weather, and a venue for developing real-time links between abstract principles and visible occurrences. With the advent of the internet, teachers who wish to leverage the atmosphere as a teaching tool now have a world of information at their fingertips. However, personal experience suggests that these connections are not being made in some secondary science classrooms. Many undergraduates struggle to form scientifically correct explanations of weather events, and are unable to connect theories of energy and matter with actual phenomena. I’ve noticed this frequently in my career as a captain of sail training vessels, and further observed that lessons on weather, when taught, often aren’t retained after the fact. Topics related directly to the water cycle frequently seem most problematic. What’s in a cloud? What is fog? Why do some clouds make rain, while others don’t? Why does it get suddenly cloudy in the evening at sea, a time of day when sailors traditionally get out their sextants in the hope of glimpsing a navigational star?

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This study was undertaken with several samples of undergraduates, and research questions were defined with the goal of learning more about how students approach the topic of weather: First, what is the general level of literacy among college students regarding the water cycle and basic weather phenomena? Have they really received the level of preparation suggested by the learning standards? Is there uniformity in this regard among the general population of undergraduates, or are some better prepared than others? Second, what seem to be the chief cognitive barriers to understanding? Do they conform to past findings in the literature? Is it possible to identify any crux concepts, with their roots in the physical fundamentals of the hydrographic cycle? Finally, what is the best way to teach these concepts? Do lectures work? Can any measurable gain be made with the addition of inquiry-based, “student centered”, learning materials to the curriculum? In the spring of 2006, interviews were conducted with six University of Maine students in an introductory course in meteorology, to measure their initial understanding of evaporation, condensation, and cloud formation. Data from the interviews supported several findings from the literature; most notably that students often do not visualize condensation as clearly as they do evaporation (Bar, 1994), and that reciprocal processes (e.g., evaporation vs. condensation) are often not well linked in the cognitive process (Gopal, 2004). Also noted among the interview subjects were a commonly held, but incorrect, belief that water in its vaporous state was sometimes visible to the eye, and a general difficulty in recognizing the ambient presence of water as vapor in the air column.

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Subsequently, surveys derived from the interview data were distributed to a larger sample of undergraduates. Pre- and post-instruction data were compiled for two sections of an introductory geology course at the University of Maine, while, during the same period, identical instruments were administered as pre-tests to students of “Woods Hole Sea Semester”, a prominent field study program in oceanography. After testing, an analysis of pre-test scores showed no statistical difference between the three samples, indicating a consistent, and rather low, level of initial literacy in the focus topic. A review of scores showed a recurrence of several “misconceptions” consistent with findings from the literature, as well as those noted in the interview phase of this research. Finally, testing of post-scores showed a small favorable effect in cases where inquiry-based instruction was given as a supplement to lectures, suggesting that a possible gain resulted from a more student-based approach to the material. The results of this study indicate that more could be done at the secondary level to see that students are able to take what they’ve learned in their chemistry and physics classroom, and apply it to their understanding of earth systems. Furthermore, the route to better understanding may lie in the use of lessons that encourage students to build their own bridges between fundamental scientific concepts and the world that they observe. The greatest challenge to the researcher remains that of understanding how the students think, and what methods of presentation truly yield the best results. Several methods were tested in this survey, and recommendations are made for future investigations.

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Chapter 2 Student Understanding of the Water Cycle: A Review of the Literature

2.1.

Abstract

This review of the literature was conducted to assess the current progress of educational research regarding the phases of water, weather, and the use of earth systems as a teaching framework for more fundamental scientific concepts. Relatively little has been written directly about weather, though the work of several authors names the atmosphere as one of several earth systems with a high potential for collectivizing the instruction of scientific principles. Researchers focusing directly on the water cycle make note of the early, and sometimes confounding, experience that students develop in viewing the day-to-day manifestations of phase change. Frequently, student explanations become more confused when wedded to formal instruction. In secondary and undergraduate science students, a cognitive divide exists between visible processes(evaporation, melting) and abstract ones- (condensation). Finally, in the case of weather, the views of students are shaped by a combination of what they have seen, and what they’ve been formally taught. Several researchers argue in favor of instructional examples that encourage correct recall of the fundamentals of aqueous phase change, and that are designed to mesh directly with everyday observations.

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2.2.

Introduction

The “water cycle” is a collective title given to the transition of water among its three phases, as a part of specific earth-systems processes. In the classroom, there is frequently a topical separation between the terrestrial and the atmospheric components of the cycle, though they are directly linked as processes. The series of transformations involving the air column was chosen for the initial focus topic of this study, given its central importance to meteorology, and its prominence in both the formal and pre-formal stages of scientific learning (Bar, 1989, 1994). While research into how students model the atmosphere and its subsidiary concepts is not extensive, the literature indicates several clear trends. First, there is a significant level of student misunderstanding with regard to atmospheric topics at all levels (Henriques, 2002). Some of these misconceptions are internally driven, some are the product of flawed primary instruction, and still others stem from a faulty mating of theory and observation. While the term “misconception” has broad meaning in educational research, examples will show a divide between a rich supply of “wrong facts” and a much more complex field of faulty constructions. Second, it appears that early learning of water-related concepts follows a path that is well described by the constructivist language of Piaget (Bar, 1989), and that hinges on other identifiable benchmarks in cognitive development.

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Third, the assimilation of formal theory in older students is hampered by a clash with accumulated experience, and an instructional failure to identify and address key concepts at the pre-formal stage (Gopal, 2004; Osborne, 1983). Data reported by these authors point to problems with some commonly chosen teaching examples, and faulty assumptions about how certain cyclical processes should be represented in texts and syllabi. Finally, cases are made for the use of earth systems as an integrating framework for the teaching of scientific processes (Mayer, 1995; Ben-Zvi Assaraf, 2005). In light of the literature, the atmosphere may hold potential as a system for the unified instruction of physical principles, one that can advance in step with phases of cognitive development, and be used to connect abstract models with direct experience.

2.3.

Meteorological Misconceptions

The study of weather is an interdisciplinary field, governed by the laws of chemistry and physics, and categorized mainly by the study of climate, the earth-sun relationship, and energy transfer (Henriques, 2002). Henriques enumerates the cognitive and pedagogical challenges of atmospheric study, and supplies a draft list of misconceptions as a potential aid to instructors. A caveat is given regarding the nature of different misconceptions, which might take the form of “wrong” facts, flawed models, or principles borrowed from elsewhere and misapplied. Such “borrowing” is made more likely by the multidisciplinary content of meteorology, and can, as we will see, work either for or against correct understanding.

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Aron et al. (1994) provided a study of “atmospheric misconceptions” among a population of students in grades 7-15, based on survey data from a multiple-choice pretest instrument. This research serves to detail some distinctive subtypes residing under the broad moniker of “misconception”. Students who claim to know that “lightning never strikes the same place twice” might merely be the victims of urban legend, while other misconceived answers point toward more complex structures of misunderstanding. Nearly half of Aron’s subjects failed to note the inverse relationship between pressure and altitude, perhaps indicating an incomplete grasp of what actually produces atmospheric pressure. A question regarding the visible contents of a cloud yielded a similar number of incorrect responses. Over a series of three papers Bar et al. (1989, 1991, 1994) examined the early development of water literacy among elementary and secondary students, with the goal of recognizing distinct formal and pre-formal benchmarks of understanding. Drawing on the work of Piaget & Szeminska (1952), Bar et al. suggested that the concepts of “conservation” and “air” must be assimilated before things like evaporation can be correctly modeled. Prior to this point, children maintain the notion that evaporated water has simply vanished. According to the study, recognition of conservation appears first, allowing students to move beyond the simplest explanation, “water disappears” to an acceptance that the water has gone “somewhere”. The concept of “air” emerges subsequently (Piaget, 1972), and, when internalized, allows for an acceptance that the water can go somewhere that’s “up” (evaporating) as well as “down” (into the ground). This notion is more sophisticated, and might be seen as a step toward recognition that water needs to take on another “form”, in which it can coexist with air. This assemblage

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of concepts then forms the framework for a more formal understanding of state change in water. In this way, Bar’s “stages of understanding” resemble the phases of conceptual change enumerated by Posner et al. (1982), as they are elements in a series of revelations that pave the way for a more complex model. What happens to these pre-formal concepts when they encounter instruction is addressed specifically in Bar et al. (1991). This study showed that secondary students have difficulty when asked to apply new, more abstract, concepts to what they’ve seen and thought historically. Subjects in this research were at times misled by the scientific terminology that was intended by instructors to lead them to the next level of understanding. To address this, Bar et al. divide their terminology to distinguish between alternative views, empirical models that precede formal instruction, and misconceptions, categorized as products of misleading and/or misapplied information from formal instruction. Bar et al. use cross-comparisons of multiple-choice and freeresponse data to show that many “misconceptions” seem prone to appear in multiple choice responses, but not in open-response answers from the same students. The authors suggest this trend as an indication that students may be swayed by “scientific” language, even when they are unsure of what it means. The reciprocal concept of condensation proves an even greater challenge to students than evaporation. Here, even undergraduates have difficulty recognizing the conversion of airborne water vapor to a precipitating liquid phase. Gopal (2004) and Johnson (1998) blame this difficulty on the lack of a concrete visible mechanism, and argue that similar issues exist for water evaporating in the absence of a heat source, as is often the case in atmospheric processes. In fact, the essential notion that water vapor is nearly always

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present in the air seems elusive to students, and only with a series of faster-acting experiments using more volatile liquids is Gopal able to trigger what he terms a “conceptual change” in many of his subjects. Perhaps because of this difficulty, many undergraduates maintain the incorrect prerequisite of a temperature gradient for evaporation in an open system (Gopal, 2004). Even those with a correct molecular understanding of evaporation were prone to this misconception. In this case, microscopic understanding is not a magic bullet, as it may easily be “assimilated” (Posner et al., 1982) with the (conditionally correct) heat prerequisite without conflict. Gopal’s insights are interesting in two regards, as they illustrate the power of concrete examples over abstract models, and show that an understanding of correct microscopic theory is not necessarily enough to ward off incomplete assumptions on a larger scale.

2.4.

Approaches to Instruction

While a student may “learn” by rote explanation that clouds are made of “liquid water droplets and/or ice crystals”, a proper understanding of this question hinges upon a correct model for how water moves between phases in the atmosphere. Because all students, merely in watching the weather go by, have built a long history in witnessing iterations of the water cycle, their cognitive models are likely formed by personal experience as well as by prior teaching (Taber, 1998). This “viewability” sets phase change apart from many other chemical processes, and provides something of a twoedged sword to the instructor: The world is rich with resonant examples, but a student’s views are likely to be prejudiced by their own history of observation.

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Given a constructivist approach to teaching, Bar et al. (1989) argue that productive formal instruction must be synchronized with recognized stages of cognitive development, and stress the series of important “accommodations” (Posner et al., 1982) with regard to the water cycle that take place between ages 5-12. Bar agrees with Posner’s advocacy of relevant contextual examples. Students, she says, have no reason to prefer the correct scientific view if it contradicts their experience. Data from Bar (1989) and Osborne (1983) suggest that a higher rate of comprehension occurs in cases where concrete examples are available for students to see. This finding is indicative of some of the cognitive challenges involved with teaching and understanding changes of state in water, particularly in open atmospheric systems. As Osborne indicates, one can’t “see” the transition from liquid to vapor, as water vapor is invisible, and the change happens slowly at room temperatures. A constructivist learning experience based on steaming kettles and hot laundry tubs (Bar, 1989) reinforces this difficulty. Dew evaporating on a sunny morning, or water boiling in a saucepan, are both rapid processes that tend to lead students toward an assumption that evaporation must involve a temperature gradient (Johnson, 1998), while room-temperature evaporative processes (the dog’s water dish, sublimating snow) don’t happen measurably as we watch. The visible matter typically referred to as “steam”, often associated with evaporation, and errantly called “water vapor” by some, is actually liquid, and usually the result of a second, condensing, phase change. Gopal (2004) suggests that the general emphasis on energy gradients in physical science instruction is one possible trigger for misconceptions about evaporation. The concentration gradient, with equally appropriate applications to the topics of vapor

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pressure and phase change, is left unconsidered by his students in their responses, indicating that they either do not understand it, or, more likely, have not had time to reflect. Gopal takes this opportunity to admit that most undergraduate science syllabi are too dense and expansive to allow any deep consideration of the material, and instead encourage rote digestion. Another drawback in current instructional methods in physical science is a general under-treatment of reciprocal processes, (Gopal, 2004) in which reverse processes are simply explained away as opposites. Merely knowing that “condensation is the reverse of evaporation” is not enough to make it understandable to students, as they are far from mirror images of one another in appearance.

2.5.

A Systems-Based Model of Instruction

One alternative to tightly focused and context-poor science syllabi may lie in the use of large natural systems as a framework for integrating content with broader applications and observations. The visible part of a cloud is not water vapor, but a mixture of water droplets and ice crystals. Clouds form, dissipate, and, occasionally, yield precipitation, as a direct result of evaporation, condensation, and freezing over a range of temperatures. Rather than teaching this to students as theory, and asking them to graft it to experience and intuition, several cases in the literature argue in favor of using observations as the starting point for progressions into more fine-grained material. The water cycle meets the definition of a “system”, as posed by Ben-Zvi Assaraf (2005), in that it is an “entity that maintains its existence as a whole through the interaction of its parts”. Ben-Zvi Assaraf noted that students in a broad, context-based,

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instructional unit on the water cycle showed a distinct improvement in their ability to form mental models of complex processes, and were better able to identify and anticipate relationships among components than students taught in a purely topical format. The concept of reciprocal processes (Gopal, 2004) became clearer, as did the notion of cyclical ones. These revelations are meaningful from a teaching standpoint, as a large number of observable physical phenomena represent either equilibrium states or cycles, without clear start and finish points. Another compelling case for including earth-system examples in science education is made by Victor Mayer (1995). Mayer argues that a reductionist approach to science, fostered by technocratic impulses in modern society, has degraded the ability of students to think in terms of systems. While Mayer’s interests show a distinct measure of humanistic motivation, he argues convincingly in favor of the use of earth systems sciences- (geology, atmospherics, oceanography) as tools for integrating material across topical and temporal divides. While careful to cite some scientific advances born specifically from the study of complex natural systems, Mayer’s main argument is educational. Students must be able to understand science in the context of the world around them, and should have the means to attach theoretical knowledge to a working web of comprehension. In this aspect, Mayer’s thesis fits well with that of Vygotsky (Byrnes, 2000), if one presumes that there can be no “scaffolding” that is more universal or ubiquitous than the earth itself.

2.6.

Earth Systems and Visual Representation

Gobert (2000) and Dove (1999) discuss a common quality of many earth systems, which is that they are often easily represented by drawings, as well as with words and

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equations. As Dove indicates, the use of drawings may tap a holistic understanding that serves as an alternative to verbal expression, giving some students the opportunity to draw what they may not be able to articulate. In her discussion of plate tectonics, Gobert investigates the usefulness of drawings as a pre-assessment tool, and as an orienting task for study. While the latter’s results do not prove the outright superiority of drawings as an orienting task, they show at least parity with other methods, supporting Dove’s assertion that graphics are a useful descriptive tool for geoscientific applications. My personal experience in teaching science has shown this to be true. Many students can “draw” a correct explanation for something that they can’t articulate. Others benefit from the ability to alternate between verbal, visual, and mathematical modes while learning or explaining. During my research interviews, the presence of drawings, and drawing tools, often seemed to stimulate progress where an impasse would otherwise have resulted. Further, drawings of natural phenomena often elicited comprehension of theoretical material that was initially out of reach to the student. This is hardly surprising, given the volume of information that people assimilate visually in their lives, much of it from the natural world.

2.7.

Integrating Material over the Educational Timeline

Gobert’s work (2000) at the elementary level indicates the longitudinal potential of teaching units based on earth systems. Planetary geology, density, and convection were introduced to primary students in a contextual format, aimed at, or just above, their level of cognitive sophistication. This supports an objective advocated by Mayer (1995) and Resnick (1987), e.g., the use of an integrated framework for teaching science across a unified scheme. If Mayer, Resnick, and Posner (1982) are all correct, the methods

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employed in primary classes by Dove (1999) and Gobert (2000) should leave their students prepared to assimilate more sophisticated topical materials when the time comes. If taught rigorously, and with a careful avoidance of convenient but incorrect explanations, there is no reason why a primary education in earth systems cannot become the reference structure into which more formal concepts are filed later.

2.8.

Conclusions

Literature reviewed for this thesis indicates that the understanding of observable atmospheric processes is heavily influenced by the experience of students before formal instruction, and by the uptake of anecdotal information. Their transition to a formal understanding is hampered by the fact that theory does not always displace empirical concepts, and by difficulty in recognizing through observation that many natural systems are cyclical, and/or react slowly. Instructors should be wary of the “boiling kettle”, and avoid examples that support old observations while blocking the accommodation of broader applications. Molecular models for state change are useful as tools for understanding, but may still coexist with misconceptions in certain cases. Complete attention should be given to both paths in the reciprocal processes of condensation and evaporation, and care should be taken to identify examples that are only conditionally correct, particularly those that do not apply to open systems at ambient temperatures. Finally, the water cycle, manifest in the atmosphere as clouds, evaporation, and precipitation, appears to be an effective educational model for integrating the concepts of aqueous state change, heat, and equilibrium into a contiguous framework. Given their

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resonance with the life experience of students, meteorological examples meet the constructivist criteria for the ample use of analogies, metaphors, and models, and the employment of multiple contexts in the representation of material. Science instructors should leverage them accordingly.

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Chapter 3 Interviews with Earth Science Undergraduates Regarding Models for Cloud Formation

3.1.

Abstract

In this investigation, six undergraduate participants in an introductory meteorology class at the University of Maine were interviewed to assess their understanding of cloud formation and aqueous phase change in the atmosphere. A subsequent review of interview transcripts indicated at least a partial level of comprehension among all students, but also showed considerable confusion regarding the sources of condensate in the air column, and frequent misapplications of the general physical principles that underlie phase change. As noted in the literature, many student misconceptions appeared to be driven by flawed attempts to reconcile observed phenomena with scientific theory. Furthermore, many individuals presented incorrect but very resilient ideas about the physical appearance of water in its different states.

3.2.

Introduction

This series of interviews was designed to investigate how well undergraduates understand the processes of evaporation and condensation, specifically as they apply to the formation of clouds in the atmosphere. Little exists in the literature that specifically addresses how students understand the weather, particularly at the secondary and undergraduate levels. In an omnibus survey,

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Aron et al. (1994) cataloged a series of myths and misconceptions regarding the atmosphere, work that is cited by Henriques (2002) in her own review. The latter acknowledges that much of what there is to know about how students view the atmosphere must be drawn from more generalized examinations of overarching concepts like the water cycle. The findings of such research indicate that phase change, rather like the physics of simple motion, is an area where individuals build explanations from a combination of observation and doctrine. Sometimes these combinations are correct, sometimes not. Older individuals, with more formal training, are frequently more confused. Osborne and Cosgrove (1983) found wide disparities in the views of children about the nature of evaporation, and even less consistency with regard to condensation. The work of Bar et al. (1989, 1991, 1994) describes the cognitive progress of children’s “water literacy”, paralleling it to the assimilation of other fundamental scientific concepts, most notably particle theory, and the conservation of matter. Johnson (1998) identified what may be an important step in understanding weather, which is the conceptual divide between water processes taking place at ambient temperature, and those that occur in the presence of a heat source. Gopal (2004) examined phase change and vapor pressure as prerequisites for students of chemical engineering, and noted the particular challenge of understanding condensation. As with Ewing and Mills (1994), Gopal discussed the abstract nature of condensation as a concept, and posited that reciprocal processes are often inadequately covered by texts and instructors.

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Thus, the goal of these interviews was to determine the extent to which student’s views of cloud formation were influenced by some of the cognitive challenges noted in the literature, most notably those of Johnson (1998) and Gopal (2004). Are evaporation and condensation in the atmosphere harder for students to model because they take place at ambient temperatures? Further, is the “invisible” process of condensation a challenge for students to accept? What casual observations have led to misassembled explanations? Finally, are any other “crux concepts” present, fundamental misunderstandings that form barriers to greater comprehension? Interview questions were phrased as weather scenarios to encourage thinking about entire natural processes, and not isolated events. While the water cycle was the focus topic of the investigation, branch questions were used, where applicable, to probe subjects’ understanding of related concepts.

3.3.

Materials and Methods

3.3.1. The Interview Classroom ERS 140, “The Atmosphere”, is an introductory earth science course at the University of Maine. ERS 140 is generally taught annually to one section of 10-20 students, and is normally presented as a mix of PowerPoint-based lectures, and laboratories. In the latter, students use simple techniques of graphing and algebra-based calculations to interpret real-time weather data, either from local observations or the Internet. In the spring of 2006, nine students were enrolled in ERS 140, about 40% of who were majors in some branch of the physical or natural sciences. The others were registered to fulfill a university requirement of at least two semesters of credit in a laboratory science for all graduates.

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3.3.2. Interview Questions During this period, interviews were conducted using draft versions of questions derived from my literature review. Interview questions were designed to consider primary components of the water cycle, and composed to meet at least one of the following criteria: 1. The question was connected to an observable atmospheric process with which the student had at least anecdotal experience. 2. The question was designed to approach some of the cognitive challenges with regard to phase change already noted in the literature. 3. The question contained links to some fundamental physical or thermodynamic principle. 4. The question was phrased in terms of a larger mechanistic process, and offered several avenues for explanation by the student. (e.g., analogs, diagrams, direct oral explanation.) Pursuant to this, two main question stems were derived, each conceived to offer multi-dimensional coverage of the core concepts of the hydrographic cycle: evaporation, condensation, latent heat, adiabatic temperature change, saturation, and equilibrium. “Branch questions,” designed to measure specific understanding of key points, were also included.

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I.

Question 1 “Consider the Pacific coastal city of Seattle. Seattle is famous for its rainy climate, while eastern Washington is a near-desert. Why is this the case?”

This question was posed verbally, and then supplemented with a simple sketch showing the zonal geography of Washington state, including ocean basin, coastal mountain range, and inland plains. The mechanism present in this example offers students the chance to recognize several steps in the hydrographic cycle, some very basic, others more subtle: Water is evaporated from the Pacific Ocean, carried inland by the sea breeze, lifted orographically by coastal mountains, and re-condensed as clouds and rain by adiabatic cooling. In crossing the mountains, air is thus “dried out” by condensation and precipitation, and then warmed adiabatically as it descends into the inland region. Taken together, the reduction in moisture content and increasing temperature make rain east of the mountains far less likely. The aim of this question was to give students the chance to recognize oceanic evaporation as a main source of atmospheric moisture, and to note lifting as a main mechanism for cooling and condensation. I was curious to see how aware students were of the extent to which air masses could be altered by topography, and to ascertain their general understanding of the relationship between the temperature of an air mass, and its capacity for water vapor. Finally, students were encouraged to discuss the thermodynamic mechanisms behind temperature change in the atmosphere.

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After being given the initial sketch by the instructor, students were encouraged to use drawing as much as they wished as an aid to explanation.

II.

Question 2

“Which of the following would you expect to produce fog, and why?” a. warm air moving over cold water b. very cold air moving over cold water c. warm air moving over warm water d. cold air over warm ground

Question 2 was designed to look directly at how students viewed the mechanisms of evaporation and condensation, and to assess their visualization of water in its liquid and gaseous states. The geographical context for this question was more localized. Maine is a rural state with an extensive marine coastline, and many lakes and rivers. Despite large seasonal variations in air temperature, both marine and inland water masses tend to remain fairly cold. This combination of circumstances leads to frequent instances of fog, from a variety of mechanisms. Among the answers, “c” is a distractor, while the others all represent cases for the three primary categories of fog. (advection fog, sea smoke, and radiation fog, respectively) In each of these cases, the mechanism for fog is different, and represents a chance for students to explain their thoughts on how water vapor is taken up by the air column, and when it will be released as liquid.

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Answer “a” represents the most common cause of summer fog over bodies of cold water: Warm air, with a relatively high moisture content, is advected over cold water, and the layer of air closest to the water is cooled below its saturation temperature. At this temperature, known to meteorologists as the ‘dew point,” a portion of the water vapor is released as condensation, forming fog. Answer “b” describes a common winter scenario in Maine harbors, as well as on the river that runs through the University of Maine campus. Here, a layer of frigid arctic air sits over water that is just above freezing. The water, in this case warm relative to the air, is evaporating, and a portion of the evaporate re-condenses as droplets, or “steam” before being re-evaporated. A key conceptual difference between answers “a” and “b” is the source of the fog condensate. In “a,” fog is the product of ambient water vapor within an air mass, while in the case of “sea smoke,” the water for the cloud is being generated by the water mass. Answer “d” describes a mechanism closely related to that for “sea smoke”, but where a warm mass of earth is substituted for a body of water. As the ground cools by radiation, a rising current of warm air carries water vapor that is then condensed when the dew point is reached. These questions were used as the basis for a series of half-hour interviews with six of the nine students enrolled in ERS 140. The remaining three declined to be interviewed. Interviews were recorded and then transcribed. Much of the material contained in the interview questions was covered within the instructional context of ERS 140. Due to the logistics of scheduling, subjects were at different points in the instructional process at the time of their interviews. I tried to be

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mindful of this, and to adjust the dialog accordingly, with the primary goal of identifying recurrent cognitive issues, not quizzing students on terminology.

3.4.

Results and Discussion

Several students from the interview group had difficulty with the concept that airborne water vapor can serve as a source of condensation. Instead, they felt the need for a nearby reservoir of liquid water to get things started. Most balked initially at the notion that fog could be produced by a layer of warm air over cold water, (the most common scenario in Maine) because cold water “lacks the evaporative energy” needed to make water vapor. A few had experience with this type of fog, but could not explain the mechanism. A few examples from the interview transcripts illustrate this. The interviewer, “I”, is the author in all cases. Different subjects are shown by initial. (C, B, Z, etc.)

I: Let’s talk about fog now... (sketching) what I’ve drawn here is a series of lines that represent an air/water boundary… D: Well, if this was water, this is air... (pointing) if water were a lot colder, enough so that when the air goes over the water, it wants to balance the energy as much as possible, so the heat goes from the air into the water, it makes the water begin to evaporate. And we get the fog, that’s water vapor that’s coming off the water, that’s beginning to evaporate. A lot of times, you can get fog when the air isn’t so warm that it can absorb a ton of moisture, and instead the water vapor, it’s going to come up and just kind of hang over the water… cause with all the high temperature

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over the low temperature, it just creates so much more vapor. The water is so ready for energy, and the air is so ready to give... so they can balance the energy. And when that happens, the water molecules that get most of the energy are going to want to turn into a vapor... but being so close to water still, they’re not going to totally escape, either. It’s kind of like a cycling process right above the water, between the water and the air layers, where you have energy from the air, causing evaporation off the water, as that evaporation rises, it cools again, and doesn’t get away... the air has enough moisture so that it’s not gobbling it up, to reach saturation, and the air is warm enough so that it can keep giving energy. It’s saturated air, it’s going to have much more energy to give than if it isn’t saturated... because of the higher specific heat... so there will be moisture evaporating off, letting it cool, and the re-evaporating so that you have a low layer of dense water vapor. I: Any other combinations? D: I guess if it was reversed, if the water were a lot warmer than the air, then it would be... the air was cold, it would be taking heat from the water, but I don’t think that it would be evaporating anything from the water... that’s all I could think of. In this case, D has a well-developed vocabulary in chemistry, and is familiar with the concepts of solution, specific heat, and saturation. However, he is focused on the temperature gradient between water and air, and views the fog as a by-product of evaporation caused by this gradient: D: When the air goes over the water, it wants to balance the energy as much as possible, so the heat goes from the air into the water, it makes the water begin to

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evaporate. And we get the fog, that’s water vapor that’s coming off the water, that’s beginning to evaporate. A lot of times, you can get fog when the air isn’t so warm that it can absorb a ton of moisture, and instead the water vapor, it’s going to come up and just kind of hang over the water.

This explanation thus categorizes fog as water vapor that has been evaporated from the surface, but that the air is not energetic enough to absorb. D is confronting two conceptual obstacles here. First, he is considering water vapor to be visible, at least while in some intermediate stage before it is fully evaporated. Second, he is failing to recognize the air column itself as a potential source of water, and to see that the condensing of fog may be the reciprocal process of an evaporation that took place at some other unknown place and time. The literature (Bar, 1989; Gopal, 2004) suggests that this bias may be the result of observation, as most students have witnessed “fog” in the form of steam, rising from warm liquids. The cases of “sea smoke” and “ground fog” are both examples of this, where radiative cooling causes warm, moist air to rise and cool, releasing vapor as condensate. However, an example from another interview shows a reluctance to adapt this concept more broadly, to a case on a winter day where a body of seawater, though too cold for swimming, remains quite warm in comparison to the air: I: So you have very cold continental air moving over the Gulf of Maine, which is... C: 33 degrees? I: Yeah, not much colder than that.

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C: So there’s a temperature difference… I don’t think there’d be enough to create fog. I’m basing this on experience, not on something technical. I: Sure. That’s how most of us learn about weather, isn’t it? C: So when it’s below zero out, there’s no clouds, it’s really really dry, you’re chapped… I: Why do you think that is? C: Well, we’ve talked about temperature differences, and moisture in the air, so, the warm air with moisture in it touches cold air, that’s when it will go from the vapor state to the liquid state, which we can see. So, if it’s really cold, I’m thinking, maybe the air has no moisture in it. (Here C has correctly recognized the relationship between temperature and the potential of air to hold moisture.) I: So if we talk about the sea surface, liquid water, which can’t be any colder than say, about zero C, with the very cold dry air over it, what’s that boundary going to look like? We’ve talked about gradients… what are gradients in temperature and moisture going to look like? Give a little thought to what’s going to happen in the boundary layer here. C: The thought that I have, if the air is colder, it, has less stored energy… it doesn’t have the ability to pull moisture off the water. However, in this last exchange, C reiterates the conviction that evaporation must be driven “from above.” As with the warm-air-over-cold-water scenario, (the student thinks) fog is produced by air “pulling” vapor from the surface.

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Inherent in these examples is confusion about the difference between the gaseous and liquid states of water, and a well-entrenched belief that water vapor is visible to the eye, at least sometimes. This misconception seems to block understanding of where and when phase changes are taking place. I: OK, what do you think of when you’re looking at a cloud? D: Air and water vapor... air, with water trapped in it. When I was younger, I thought of it as actual physical droplets... but now, after chemistry class, I think of it as how you can saturate one liquid with another. I think of them both as gasses, saturating one another. I: OK. D: Vapor is a gas, and air is a gas, so they can be combined, like you can combine liquids. I: Any sense of why some clouds have rain under them, and some don’t? D: That... seems to have to do with the kind of temperature change a cloud is going through, and how much moisture is actually in it. Like, think of chemistry. if you’re adding salt to water, like the vapor is the salt, you’re adding it in until it reaches the point where you just can’t add anymore in, and then if you were to strain that out, you’d get salt. I: OK D: The water just can’t take any more soluble salt. That’s how I saw it. I: So, like a saturation point. D: Right. The cloud gets saturated to a certain point, it just can’t take anymore… and, that depends on temperature, like, I know that if you heat up a solution, it can

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take more salt. A cloud, it’s the same thing, if you heat it up, it can take more moisture, depending upon where you are in the atmosphere. They do move up and down. Like a cloud is OK at one level, but if you move it, change its level, it cools off and can’t hold as much moisture. I: OK.. What is your sense of what fog is? D. It’s essentially a cloud, just lower... kind of like, just, water vapor, caught up in air. And it’s got a high enough ratio of water vapor to air so that it’s actually visible… or somewhat tangible. I: So it’s like a cloud, sitting on the ground? D: Yeah. In these examples, D draws on his experience with solutions to explain the behavior or water vapor in clouds. However, he has placed the analog of “saturation” in the wrong place, in that a cloud already represents air that is beyond saturation with regard to moisture. This is a confusing concept to students: The fact that not all clouds yield rain, or “real” liquid water, suggests the existence of some intermediate phase of water that is not really there. Another student, Z, has a nearly complete view of cloud composition: I: What is the composition of a cloud? Z: Water vapor, necessary for condensation, water droplets, ice, if it’s cold enough, smoke, if the particles are small enough... you have solutions, like smog. There have to be water droplets, since the rain has to come from somewhere. I: If a cloud has water droplets in it, is it always raining when it’s cloudy? Z: Um, it depends on the differences in the water droplets.

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I: So what would the differences need to be? It’s cloudy outside today, but we didn’t get wet on the walk over here. Why? Z: Well, if the cloud is large enough to hold its vapor until… Rain clouds are large clouds where the water vapor all comes together and condensing into larger and larger droplets until they are too large to be suspended until they begin to fall. Correct. But Z remains unclear on the appearance of different phases of moisture, incorrectly attributing a conditional visibility to water vapor. I: Which of those can you see? Can you see water vapor? Z: In certain conditions, like if it’s cold outside and you breathe… You see your breath, cause it takes less water vapor to make a cloud when it’s cold. On a warm day, you don’t see it, because the vapor is absorbed by the air. In this exchange, Z is explaining that your breath on a cold day is somehow “excess” water vapor that the air can’t “hold”. Yet it remains “vapor” in his mind, since it apparently remains airborne. This erroneous view might be described by the assertion that “all airborne water is vapor”. This confusion appears to be prevalent, as evidenced by the end of an exchange with T, another student with a sophisticated view of cloud formation: I: Any sense of what happens to the water between this stage (west of mountains) and this point (east of mountains)? Here, (west) the moisture is in the air, but up here, it gets to a state where you can see it, feel it. What has happened to cause this? T: Well, it’s like a water vapor. Evaporation, and then condensed into a liquid right there, makes it rain.

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I: Ok, so the clouds are the product of the condensation. But you’re not really sure of why that happens, other than that the cooling of the air is something that encourages the condensation? T: Yeah. I: So what’s in a cloud? T: Water vapor, water droplets. I: By water droplets, you mean liquid water? T: Yeah, condensing water, because that’s where it changes from a gas to a liquid. I: So, if you are looking out the window at a cloud, what would you say are the components of a cloud? T: Mostly, ah water vapor. In addition to this persistent conviction that clouds are mostly “water vapor”, T is unsure of why phase changes are connected to temperature and energy: I: OK, what is it about warm air that allows it to hold more moisture? T: I’m not really sure about that. I: Ok, So the clouds are the product of the condensation, but you’re not really sure of why that happens, other than that the cooling of the air is something that encourages the condensation. T: Yeah. Correct, or nearly correct, molecular explanations for phase change were given by about a third of those interviewed: I: If I were to draw a drop of liquid water, what do you think is involved in the process of that water being evaporated? What’s going to happen there?

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J: Well, heat would be produced by whatever source, and it would gain kinetic energy, the molecules, and they would start moving fast enough to where they had enough energy to lift off, and become vapor. I: Ok, so the faster molecules would escape? J: Yeah, because they have more energy to do that. I: How long would that process go on? J: Until the whole droplet was evaporated, was all vapor. I: If you had vapor molecules vs. liquid molecules, how would you describe the differences between the molecules, as they appeared? J: These (vapor) would have more kinetic energy, as they have a higher temperature. They wouldn’t be compressed though, if it’s just a regular atmosphere, above a water molecule, they’d dissipate. I: So they would spread out, if you didn’t have some kind of enclosure around them? J: Yes. I: More space between the molecules? J: Yeah. Even students with a more sophisticated understanding of evaporation had difficulty with adiabatic temperature change, and in recognizing changes in pressure as part of what affects the temperature of an air mass. J: The winds would bring in water vapor from the ocean, and then it would probably get lost due to the condensation, up here (points to mountains). I: What’s producing the condensation? J: Up here?

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I: Yeah. J: The lifting condensation level… it varies. I: Want to explain that process? J: As the air elevates, the temperature drops, and at a certain point, the temperature drops to where the air is totally saturated, and, that would be the level that clouds form from condensation. I: Can you say a little more about why the temperature drops? J: As you increase in altitude, you have the environmental lapse rate (ELR), 10 degrees C per km for dry air, and with wet air, it’s variable, 5-9C/km. I: OK J: So with the ELR, it varies per kilometer, and as the air temperature drops, it can no longer hold that moisture. The cold air holds less water, so will be come more saturated. It will have a higher relative humidity. In the previous exchange, J recognizes the environmental lapse rate, i.e. that temperature decreases with altitude in the troposphere, but fails to note that rising air is cooled adiabatically, as pressure drops and the air parcel uses up energy to expand. J also recognizes that condensation will slow the cooling rate of rising air, but he does so for the wrong reason. I: You were talking about the lapse rate, and how it changes, depending upon whether it’s wet or dry, why is that? J: The energy or heat. When it’s wet, it’ll absorb more energy, as you go up in the atmosphere. The dry lapse rate, there is nothing to absorb any kind of energy, so

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it’s going to cool faster, whereas (in the presence of) water vapor, the temperature will drop slower. It’s the specific heat, I believe. I: So, it’s kind of an analog for the maritime climate, that you were describing earlier, where the water acts as a kind of temperature buffer? J: Right I: Once you have condensation in the air, it’s taking longer to cool off? J: Yeah. Condensation slows cooling through the release of latent heat, not because wet air cools more slowly than dry air. It is correct that air has a lower specific heat than water, but in this case, the water was “in” the air all along as vapor. J seems to retain the notion that water is somehow being “added” to the air column by condensation, rather than merely changing phase. In the following example, Z identifies pressure as a mechanism for temperature change, but does not invoke any examples from thermodynamics or kinetic molecular theory to support it: Z: Well, the clouds generally appear above the mountains because of the rising air, the heat is released as the pressure goes down, it can’t hold as much water, so you get clouds. I: What is it about that process that releases heat? Z: The adiabatic cooling, that release in pressure. I: OK.. can you express adiabatic cooling in terms of the change of energy in the gas? Can you express it in terms of work? Z: No.

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I: What does the term adiabatic mean to you? Z: Is it the change in pressure? I: So in this case, you’re using the term to describe the change in pressure affecting the temperature of an air mass? Z: Yes. I: So in the case of Mountains, the as the air goes up, we’re saying it undergoes an adiabatic temperature change, it cools off as it goes up, and the moisture comes out? Z: Yes.

3.5.

Conclusions

In the context of these interviews, students had difficulty with recognizing atmospheric water vapor as a source of condensate in cases of cloud formation. Instead, they appeared biased towards “upward evaporation” as a mechanism, where a temperature gradient between air and water draws water vapor off of a liquid surface. This bias may be driven by long observational experience with “steaming bathtubs” and other vessels of warm liquid (as described by Bar, 1989), though the temperature gradient in those examples is going in the opposite direction. Thus, where a liquid surface is present, most students look for a way to name it as the source of the “cloud”, regardless of relative temperature characteristics of air and water. Confusion also existed over just which phase of water is actually represented by visible clouds of moisture, perhaps because not all clouds are coupled with precipitation. Many students attempted to classify all airborne water as “vapor”, whether it is visible or

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not. Again, this may be influenced by experience. Clouds are visible, yet they frequently don’t yield “wet” water (in the form of rain), so they must (students think) be vapor. Your breath, visible on a cold day, has come from your lungs, so any water it contains must be vapor. “Saturation”, where mentioned, was noted as the point where water vapor becomes visible, but not necessarily the occasion of a phase change from gas to liquid. An understanding of phase change at the molecular level was expressed by about half of the interview subjects, with varying degrees of accuracy. Most students who invoked molecular models successfully associated the less organized phases with greater molecular movement and the uptake of energy. Among the mechanisms for energy change that emerged in the interviews, most students were comfortable, at least in a descriptive sense, with the concepts of heat transfer by conduction and radiation. Adiabatic temperature change was a much more elusive concept, even after instruction, and was described correctly by only a few of the subjects. Among those, none drew on the language of thermodynamics to explain why lowering pressure can decrease the temperature of the air mass. Again, understanding of this abstract concept is invaded by casual experience, and the notion that “high places are simply colder” is a difficult assumption to modify.

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Chapter 4 Condensation in the Atmosphere: A Quantitative Survey of Water Literacy Before and After Instruction

4.1.

Abstract

In this investigation, a survey instrument derived from interviews with earth science students at the University of Maine was distributed to several samples of undergraduates in order to measure their understanding of the atmospheric water cycle, before and after instruction. Subsequently, survey samples were divided in order to allow the testing of inquiry-based teaching materials against traditional lecture techniques. Survey results indicated a low level of initial literacy among all samples, while a statistical analysis of pre- and post-test scores showed a significant gain where inquiry-based teaching materials were employed as a supplement to lectures. According to the results of this study, barriers to the understanding of aqueous phase change and cloud formation include the inability to visualize condensation, and a failure to identify the vaporous phase of water in certain cases.

4.2.

Introduction

This study examined student understanding of the water cycle, particularly as related to meteorological events in the atmosphere. The study subjects were undergraduate earth science students, but the concepts examined, evaporation, condensation, and simple molecular theory, are well addressed in standards for science education at the secondary level (Maine Learning Results, Chapter I). Hence, it might be expected that any graduate 38

of a college-tracked secondary education should possess a basic level of literacy in the principles of phase change, and how they lead to the formation and dissipation of clouds in the atmosphere. However, evidence from the literature, and from a series of interviews conducted with earth science students at the University of Maine (Chapter III), indicates several main threads of cognitive difficulty among students when topics related to the water cycle are dealt with. As described by Osborn & Cosgrove (1983) and Bar (1989, 1991, 1994) there is great inconsistency among students in their understanding of water-related concepts, particularly condensation. Johnson (1998) points out the very real cognitive differences that exist between “natural”, e.g., atmospheric, models of phase change, and those being driven by a visible temperature gradient, as with a boiling kettle. The latter, he adds, are generally given more attention in teaching examples. Gopal (2004) characterizes condensation as a subtle and rather intangible process, and one that may well be underemphasized instructionally, given its importance. Data from student interviews in Chapter III of this document bear out many of these findings, and add to them the observation that students are not always ready to recognize that water vapor is invisible. A general movement in science education towards context-based and inquiry-driven methods of teaching has led to conclusions that these methods, in many cases, lead to better retention of principles, and to a greater readiness among students to integrate across topical divides when considering scientific questions (Mayer, 1995; Gobert, 2004; Ben-Zvi Assaraf, 2005). Given this, one aim of this investigation was to explore the value of such an approach to the focus topic.

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Thus, the main research questions for this study were framed as follows: 1. (Chapter III) What are the most common cognitive barriers to understanding phase change in the atmosphere, within samples of undergraduate earth science students? Do these findings conform to those previously noted in the literature? 2. Is there a divergence of literacy in these topics between different populations of undergraduates? 3. For the material being studied, do inquiry-based teaching materials yield a different pedagogical effect than traditional lecture instruction?

4.3.

Materials and Methods

4.3.1. The Survey Based on the outcome of a series of interviews with six earth science undergraduates at the University of Maine, (see chapter III) a survey instrument was developed for distribution to a larger sample of students. The main survey was designed in the “multiple-choice-multiple response” (MCMR) format, in an effort to preserve some of the subtlety of the original questions, while permitting quantitative scoring and statistical testing of results. For these purposes, an ordinal scoring scale was employed, assigning value to four possible outcomes: 0 points: Incorrect answer 1 point:

Answer includes both correct and incorrect choices

2 points: Correct but incomplete 3 points: Correct

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This method of questioning and scoring was selected in the hope that students would recognize complex cases, where present, and in an attempt to measure the strength of their beliefs regarding different concepts. Furthermore, the survey was designed for use as a pre/post instruction assessment, and it was felt that the more complex format would offer a broader measure of progress in each case. The survey instrument was developed as an expansion of the interview topics from Chapter III, with questions designed either to mirror the initial queries, or to focus on cognitive issues raised in the interview process.

4.3.2. MCMR Question Design The multiple-choice questions were designed to be the primary source of quantitative scoring data, and fell into two primary categories, directed either at major mechanisms of the atmospheric water cycle, or at specific physical principles behind a process:

Question 1: In elevated regions, clouds frequently appear near the peaks of mountains, even when it is clear elsewhere. Choose the answers below that best explain why this happens. a. Evaporation of snow from mountain peaks b. Condensation of water vapor from the air c. A drop in pressure d. A drop in temperature

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This is an extract of the “Seattle” question from the interview stage, and an example of a mechanism-based question. “a” is a distractor, while “b”, ”c”, and “d” are all potentially correct. This set of answers allows a student to recognize clouds as a product of condensation, itself the result of a temperature drop caused by adiabatic cooling. An intuitive connection between “cold” and “altitude” may make answer “c” hard for some students to accept.

Question 2: Fog may be formed by which circumstances? a. Warm air moving over cold water. b. Warm air moving over warm water. c. Very cold air moving over cold water. d. A cool summer evening in a plowed field.

This is a paraphrase of an interview item, testing the level of acceptance for different mechanisms of fog and cloud production. Again, there is only one incorrect answer, (b) though interviews showed a strong resistance to the notion that fog could form in the absence of a warm water “source” for vapor.

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Question 3: (Adapted from Aron, 1994) Circle any answers that might correctly describe the visible components of a cloud. a. Water vapor b. Ice crystals c. Water droplets d. Smoke

This question involves visualization, a seemingly important tool in students’ recognition of phase changes. Here, there are two correct answers, b and c. A cloud might include smoke, but water vapor is invisible. A failure to internalize the latter may be part of why students don’t “see” how condensation may be produced from air that appears dry.

Question 4: When water vapor is condensed into a liquid, which of the following are true? a. Heat energy is absorbed by the water b. Heat energy is released by the water

This addresses the principles of phase energy and latent heat, and is designed to test the understanding that more organized phases of matter are less energetic. The

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release of latent heat during condensation is a primary mechanism of heat transport in the atmosphere.

Question 5: Which of the following are true regarding the phases of water? a. Water can go directly from vapor to a solid state. b. Water must pass through a liquid state before evaporating c. Water is always a solid below 32°F (0°C) d. Water may exist in two or more states simultaneously.

Question 5 is meant to examine how students view the phases of water. “a” and “d” are both correct. Most important is the concept that water may exist in multiple states at the same temperature.

Question 6: As water molecules evaporate, their __________ increases. a. Speed b. Kinetic energy c. Potential energy d. Size

This final question measures the student’s grasp of kinetic molecular theory, in a case connected to Question 4. “a” and “b” are correct.

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4.3.3. Open-Response Questions To supplement the main survey questions, and address some of the shortcomings noted by the literature regarding multiple-choice instruments Bar (1991), a subset of short open-response questions was included as a second page. (Appendix A) The content of these questions was meant to parallel that from similar MCMR items. For example, MCMR Question 2: Fog may be formed by which circumstances? a. Warm air moving over cold water. b. Warm air moving over warm water. c. Very cold air moving over cold water. d. A cool summer evening in a plowed field. was paired with Question 8: “The Gulf of Maine is famous for its cold waters and frequent fog. What would you expect to be the foggiest month of the year, and why?” Due to a high level of inconsistency in the results from this segment of the survey, no scoring rubric was developed, and no analysis of results undertaken.

4.3.4. Survey Sample Groups Three sample groups received the survey. ERS 102, “The Environmental Geology of Maine,” is an introductory geology class at the University of Maine, taught twice yearly, and offered primarily to non-science majors seeking to meet the school’s general education distribution requirements for science. The syllabus deals

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mostly with terrestrial geology, but generally includes a short unit on the atmosphere. “Woods Hole Sea Semester” is an off-campus field study program in oceanography, nautical science, and maritime studies, taught by the Sea Education Association (SEA) of Woods Hole, Massachusetts. SEA is accredited by Boston University, and affiliated with the Woods Hole Oceanographic Institution. Students in this program spend six weeks in the classroom, designing an oceanographic research project, before putting to sea in a research vessel. SEA students earn 11 oceanography credits per semester, and are generally drawn from private colleges across the country. The majority are juniors, and about 60% are majors in a natural or physical science. Surveys were given as pre-instruction assessments to one sample of SEA students (n= 42) and to two samples of ERS 102 (Fall 06 section, n= 34, and Spring 07 section, n=39). Both sections of ERS 102 received the survey again as a postinstruction assessment upon completion of their atmospheric unit. Between surveys, the Fall Section received approximately 2 hours of lecturing on the focus topic, while the spring section received 70 minutes of lecturing, supplemented by an inquiry-based tutorial exercise done in groups during a laboratory section (Appendix C). I gave all lectures on the focus topic. The tutorial exercise was written by me, and administered by graduate laboratory instructors assigned to the course.

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4.4.

Results

4.4.1

Statistical Testing of MCMR Scores

The MCMR sections of the surveys were scored and graded, using the ordinal scale described earlier in this section. Pre-assessment scores for all 3 samples were tested using a one-way ANOVA. Pre- and post-test scores for sections of ERS 102 were compared using a dependent-samples t-test. Effect size, a statistical quantity that measures the comparative “effect” of an educational treatment in units of standard deviation (s), was calculated for each t-test. A simple scale allows conversion of effect size to percentiles for a more tangible measure of progress under different instructional regimes.

I.

Pre-test Scores for samples SEA, ERS102 (spring) and ERS102(fall):

Mean pretest scores for SEA, ERS102(s), and ERS102(f) were 8.3095, 7.4872, and 8.3824, respectively (Fig. 4.1.). A one-way ANOVA (p critical = .05) of the three pre-test score sets indicates no statistical difference in this regard among samples.

47

14

12

Mean Total Score

10

8

6

4

2

(n = 42)

(n = 39)

(n = 34)

SE A

102S

10 2 F

0

Fig. 4.1. Mean total pre-test scores for SEA students, (dark gray) spring ERS 102 students, (light gray) and fall ERS 102 students (white). Error bars indicate one standard deviation.

48

II.

Comparison of combined pre- and post-test scores for ERS 102:

Dependent-samples t-tests show significantly higher post-test scores for both samples at the .05 level (Fig. 4.2.). For the fall section, (lecture only) an effect size of .55s was measured (71st percentile). For the spring section, (lectures plus tutorials) an effect size of .74s was measured (77th percentile).

14

* *

12 10

8

6

4

2

(n=39)

(n=39)

(n=34)

(n=34)

S_pre

S_post

F_pre

F_post

0

Total Scores Fig. 4.2. Mean total pre- and post-test scores for spring (light gray) and fall (white) ERS 102 Students. Spring students received tutorial instruction as a supplement to lectures. Error bars indicate one standard deviation. Asterisks indicate post-test results that are statistically different from pre-test results at the 0.05 level. 49

III.

Pre/post-test score comparisons by individual question:

Question 1: (fig. 4.3.) ERS102 (f) shows no statistical difference in pre and post-test scores at the .05 level. ERS102(s) shows a significant increase in post-test scores, with an effect size of .45s.

3.0

* 2.5

2.0

1.5

1.0

0.5

(n=39)

(n=39)

(n=34)

(n=34)

S_pre

S_post

F_pre

F_post

0.0

Question 1

Fig. 4.3. Question 1 mean pre- and post-test scores for spring (light gray) and fall (white) ERS 102 students. Error bars indicate one standard deviation. Asterisks indicate post-test results that are statistically different from pre-test results at the 0.05 level.

50

Question 2: (fig. 4.4.) ERS102 (f) shows no statistical difference in pre- and post-test scores at the .05 level. ERS102(s) shows a significant increase in post-test scores, with an effect size of .64s.

3.0

* 2.5

2.0

1.5

1.0

0.5

(n=39)

(n=39)

(n=34)

(n=34)

S_pre

S_post

F_pre

F_post

0.0

Question 2

Fig. 4.4. Question 2 mean pre- and post-test scores for spring (light gray) and fall (white) ERS 102 students. Error bars indicate one standard deviation. Asterisks indicate post-test results that are statistically different from pre-test results at the 0.05 level.

51

Question 3: (fig. 4.5.) Fall and spring sections both show a significant increase in scores. ERS102 (f) effect size is 1.24s; ERS102(s) effect size is .86s.

3.0

*

* 2.5

2.0

1.5

1.0

0.5

(n=39)

(n=39)

(n=34)

(n=34)

S_pre

S_post

F_pre

F_post

0.0

Question 3

Fig. 4.5. Question 3 mean pre- and post-test scores for spring (light gray) and fall (white) ERS 102 students. Error bars indicate one standard deviation. Asterisks indicate post-test results that are statistically different from pre-test results at the 0.05 level.

52

Question 4: (fig. 4.6) No significant change in scores was observed for either section.

4

3

2

1

0

(n=39)

(n=39)

(n=34)

(n=34)

S_pre

S_post

F_pre

F_post

Question 4

Fig. 4.6. Question 4 mean pre- and post-test scores for spring ERS 102 students, (light gray) and fall ERS 102 students. (white) Error bars indicate one standard deviation. Asterisks indicate post-test results that are statistically different from pre-test results at the 0.05 level.

53

Question 5: (fig. 4.7) No significant increase in scores was observed for ERS102 (f). For ERS102(s), an increase was observed with an effect size of .38s.

3.5

3.0

* 2.5

2.0

1.5

1.0

0.5

(n=39)

(n=39)

(n=34)

(n=34)

S_pre

S_post

F_pre

F_post

0.0

Question 5

Fig. 4.7. Question 5 mean pre- and post-test scores for spring ERS 102 students, (light gray) and fall ERS 102 students. (white) Error bars indicate one standard deviation. Asterisks indicate post-test results that are statistically different from pre-test results at the 0.05 level.

54

4.4.2. Distribution of Survey Answers

Table 4.1. Score Distribution for Question 1 (Correct Answers in Bold) In elevated regions, clouds frequently appear near the peaks of mountains, even when it is clear elsewhere. Choose the answers below that best explain why this happens.

Fall Pretest (n=34)

Fall PostTest

Spring Pretest (n=39)

Spring Post-Test

SEA (Pretest Only, n=42)

a. Evaporation of snow from mountain peaks

5

11

15

10

2

b. Condensation of water vapor from the air

13

26 (38% gain)

21

26 (13% gain)

28

c. A drop in pressure

13

16 (3% gain)

8

15 (18% gain)

9

d. A drop in temperature

9

21 (35% gain)

4

17 (33% gain)

8

The distribution of individual answer choices for Question 1 (Table 4.1) shows that the SEA students were the most familiar at the pretest level with condensation (answer “b”) as a source of clouds. The fall section of ERS 102 had the smallest fraction of students who made this choice on the pretest, but saw the greatest gain in score, with an additional 13 students choosing the condensation mechanism on the post-test. The number of correct pretest selections of “c” is comparable among samples, though the percent gain in post-test selections of the pressure mechanism is greater for the Spring (tutored) section of ERS 102. Both groups achieved similar gain in “d”.

55

Table 4.2. Score Distribution for Question 2 (Correct Answers in Bold) Fog may be formed by which circumstances?

Fall Pretest (n=34)

Fall PostTest

Spring Pretest (n=39)

Spring Post-Test

SEA (Pretest Only, n=42) 35

a. Warm air moving over cold water.

5

33

32 (no gain)

b. Warm air moving over warm water.

13

11 (18% gain) 26

5

1

0

c. Very cold air moving over cold water.

13

16 (9% gain)

4

12 (20% gain)

0

d. A cool summer evening in a plowed field.

9

21 (35% gain)

5

26 (54% gain)

16

The distribution of individual answer choices for Question 2 (Table 4.2.) shows that similar fractions of ERS 102 (Spring) and SEA students chose the correct mechanism described in “a”. In the post-test, only the fall section of ERS 102 showed a gain for this choice. Over a third of the fall ERS 102 section chose the (incorrect) mechanism described in “b”, and the number of selections for this choice doubled after instruction. The spring (tutored) section of ERS 102 saw a greater percent gain in correct choices of both “c” and “d”.

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Table 4.3. Score Distribution for Question 3 (Correct Answers in Bold)

Fall Pretest (n-34)

Fall Post-Test

Spring Pretest (n=39)

Spring Post-Test

SEA (Pretest Only, n=42)

a. Water vapor

30

19

31

20

34

b. Ice crystals

15

12

14

23 (28% gain) 30 (31% gain)

19

c. Water Droplets

31 (47% gain) 27 (38% gain)

d. Smoke

9

1

0

5

8

Circle any answers that might correctly describe the visible components of a cloud.

18

18

The distribution of individual answer choices for Question 3 (Table 4.3.) shows that similarly large fractions of ERS 102 and SEA students held the incorrect initial belief that clouds are made of water vapor. The distribution of correct answers “b” and “c” is also similar among samples. The fall (lecture) section of ERS 102 shows a higher gain in correct choices on the post-test, with a similar decline in (incorrect) answer “a”. This said, more than half of each ERS 102 sample maintains the water vapor assertion (“a”) after instruction.

57

Table 4.4. Score Distribution for Question 4 (Correct Answers in Bold) When water vapor is condensed into a liquid, which of the following are true? a. Heat energy is absorbed by the water b. Heat energy is released by the water

Fall Pretest (n=34)

Fall PostTest

Spring Pretest (n=39)

Spring Post-Test

SEA (Pretest Only, n=42)

9

11

10

10

11

25

23

27

26

31

The distribution of individual answer choices for Question 4 (Table 4.4.) shows a similar distribution of correct and incorrect pretest answers among all samples. No significant change in scores occurred for either sample.

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Table 4.5. Score Distribution for Question 5 (Correct Answers in Bold)

Fall Pretest (n=34)

Fall PostTest

Spring Pretest (n=39)

Spring Post-Test

16

27 (33% gain)

16

26 (25% gain)

b. Water must pass through a liquid state before evaporating

21

28

13

7

17

c. Water is always a solid below 32°F (0°C)

1

8

8

6

5

d. Water may exist in two or more states simultaneously.

4

1

14

13

18

Which of the following answers are true regarding the states of water? a. Water can go directly from vapor to a solid state.

SEA (Pretest Only, n=42) 20

The distribution of individual answer choices for Question 5 (Table 4.5.) shows a similar distribution of correct pretest choices of “a”, and a similar gain on this answer for both sections of ERS 102. However, a number of students in the fall section chose “b”, along with “a” on the post-test, despite the fact that the two are in direct contradiction. This is not the case in the spring (tutored) section of ERS 102, where a similar gain in answer “a” is accompanied by a decline in “b”. Neither of the ERS 102 sections shows gain on the assertion (“d”) that different states of water may coexist at the same temperature.

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Table 4.6. Score Distribution for Question 6, ERS102 (Spring Only)

As water molecules evaporate, their _____ increases.

Pretest (n=39)

Post-Test

a. Speed

4

b. Kinetic Energy

14

c. Potential Energy

19

10 (15% gain) 21 (18% gain) 10

d. Size

3

2

4.5.

Discussions

4.5.1. Comparison of Pretest Scores The initial literacy across all samples in the survey topics is not high, with a mean total score (from the rubric, section 4.3.1) of approximately 53%. (This is slightly below Aron’s 1994 observation of 56% for a similar, but more general, survey on weather literacy among grades 9-16.) Students seem to encounter particular problems in describing the condensation of water vapor from the air column, (questions 1 and 2) and in making a correct identification of what clouds are made of (question 3). Of those asked, few recognized the correct relationship between states of matter and the kinetic energy of molecules (question 6). A one-way ANOVA of results indicates no statistical difference at the 0.05 level in total pre-test scores between the three sample groups (Figure 4.1). This result is

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supported in by an inspection of score distributions (Tables 4.1 – 4.5), where the achievement of the three groups is generally comparable. This is an expected outcome for the two sections of ERS 102, an introductory geology class at public university, and as such populated heavily by non-majors enrolled to meet distribution requirements. However, this uniformity is more surprising in the case of the SEA sample, where the population includes a large fraction of third-year science majors from private colleges. Taken together, these results suggest that the educational shortfall is happening rather broadly, and at a pre-college level. At the least, science majors at the sampled schools are not learning anything new about evaporation and condensation after they matriculate.

4.5.2. Statistical Analysis of Pre- and Post-Test Scores A brief period of direct instruction led to a significant improvement in test scores for both samples of ERS 102 students (Figure 4.2). Students of the fall (lecture) section saw an improvement of .55s (standard errors of the mean) after 120 minutes of lecturing, a level deemed “moderate” in the literature (Coladarci, 2004). Students of the spring section received 70 minutes of lecturing and about an hour’s worth of guided-inquiry thought problems, (appendix) realizing an improvement of .74s, or “large” according to Coladarci. Converting effect size to percentile rank, recipients of the guided-inquiry materials enjoyed an apparent achievement advantage of six percentile points over the all-lecture section (77th vs. 71st percentile). The advantage of the guided-inquiry students becomes more apparent when questions are tested individually for progress. Here, questions 1 and 2 show no statistical

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difference between pre- and post-test scores for the lecture-only students, and a moderate gain for the spring group. In question 3 (what’s in a cloud?), both groups gain, with the fall group at a slight advantage. No statistical difference was observed for either group in question 4 (latent heat), while the results for question 5 again show statistically significant gain only for the tutored group. Hence, of the five questions tested for both sections, the “lecture only” group achieved statistically significant progress on only one of five, while the “lecture plus tutorial” group achieved progress on four.

4.5.3. Distribution of Answer Choices An inspection of answer distributions (Tables 4.1 – 4.5) makes the distinction between the spring and fall ERS 102 samples somewhat less clear, and the “gain” in individual correct answers is sometimes biased towards the lecture section. This is true in question 1, answer “b” (Table 4.1), where a greater fraction of the lecture students recognized condensation as a mechanism for cloud formation after instruction. In question 2 (Table 4.2), where there is direct overlap with material from the tutorial (Appendix C), the advantage for the tutorial section is more apparent in the greater gain. As was indicated by the t-test for Question 3, (Fig. 4.5), the tutorial section did no better at learning about cloud composition, and the errant choice of “water vapor” as a visible part of clouds retained a stubborn presence (>50%) for both samples (Table 4.3). Question 4 (Table 4.4), involving the concept of latent heat has only two answer choices, and as such is not an MCMR question. Similar fractions of the pretest samples answered this question correctly, but instruction yielded no gain (in fact, a small decline) in correct answers for both sections of ERS 102. The principle of latent heat was

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described in lecture to both sections, but apparently to no effect. The tutorial, designed to encourage recognition of condensation, does not address the mechanism of latent heat transfer, and thus provides the spring students with no advantage regarding this concept. The answers to Question 5 (Table 4.5) show some curious results. While both sections of ERS 102 showed comparable gain on answer “a”, regarding deposition, many of the fall group retained the incorrect and contradictory assertion stated in answer “b” (“water must pass through a liquid state before evaporating”). Deposition and sublimation are not addressed directly in the tutorial, but students from the tutored section may be inclined to think in a less “linear” way about phase change. Neither group felt comfortable with the notion that water could coexist in different states (answer “d”) perhaps suggesting that they are thinking of phase changes as “all-or-nothing” transitions, rather than equilibrium states. This would concur with the findings of Johnson (1998) and Gopal (2004). Question 6 (Table 4.6) was given as an “extra” to the spring section of ERS 102, and is not included in the statistical tests. The answer choices show that most of the students connect evaporation with higher energy at the molecular level, with some confusion about what form of energy evaporated molecules have gained. The majority of students do not link molecular speed with kinetic energy or evaporation. This is interesting, since most discussions of evaporation involve some analogy of “escape”.

4.6.

Conclusions

The outcome of this investigation indicates a low level of understanding among college undergraduates regarding the cycling of water in the atmosphere, particularly the

63

processes of evaporation, transport, and condensation that lead to the production of clouds and fog. While state and national standards (Chapter 1) specify the direct coverage of meteorological topics at the secondary level, the interviews and pretests from this study indicate a low level of prior exposure to this material, at least in any way that has led to a durable retention of correct models. The students surveyed for this study had a poor initial understanding of the water cycle, and were not well equipped to draw connections between the principles of matter and energy and the mechanisms that drive weather. This supports the conclusions of earlier authors (Aron et al., 1994; Henriques, 2002) that the treatment of atmospheric topics at the primary and secondary levels is inadequate. Results from this study also support the findings of Johnson (1998) and Gopal (2004) regarding the cognitive difficulties posed by condensation at ambient temperatures. Interview and survey data show that many students do not recognize airborne water vapor as source of condensate in the formation of clouds. This shortcoming generates models that rely too heavily on temperature gradients and liquid surfaces as mechanisms, and limits the ability of students to recognize the transport of water vapor in atmospheric systems. Subjects of this research had a limited ability to visualize water correctly in its three phases, and frequently misidentified cloud condensate as “water vapor”, a shortfall that hampered recognition of the gas-to-liquid phase change that characterizes condensation. This misconception was only partially corrected by instruction. Instruction was even less successful at introducing the equilibrium properties of phase change, and the understanding that multiple phases of water may coexist in a system at the same

64

temperature. Answers from the survey indicate that many students instead adhere to a step-like model, where all of the water molecules in a system move in unison from one phase to the next, and cannot “jump” between phases, as they do in the processes of sublimation and deposition. Teaching examples developed for the tutorial branch of this study were designed to stimulate thinking about condensation at ambient temperatures, using a series of thought problems involving both tabletop examples and natural systems. A geology class that undertook these problems as a supplement to lecture instruction saw a small statistical advantage in post-test scores when compared to a lecture-only section. These gains were most noticeable for content that directly overlapped the tutorial, e.g. fog and cloud formation, and less clear in general questions regarding the water cycle. The tutorial had apparent success in encouraging students to recognize some of the more subtle mechanisms for fog (sea smoke and ground radiation), and thus may be viewed as an effective teaching tool if directed carefully at the target content.

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Chapter 5 Implications for Future Research

At present, opportunities abound for educational researchers interested in the atmosphere. First, the data collected for this study might be further reviewed to catalog the extent, type, and frequency of meteorological misconceptions present. This study has revealed at least one prevalent misunderstanding, “all airborne water is vapor”, and perhaps another, “water cannot exist in two or more states simultaneously”. A secondary review of MCMR responses, and a revisiting of open-response data, might reveal additional misconceptions that hinge on a similar crux issues. As with the work of Aron et al. (1994), further “sorting” would be required to identify the type and durability of these issues. Are they really misconstructed models, or just bits of wrong knowledge? The most productive end of such an undertaking would be the creation of a conceptual inventory of atmospheric topics, as was done for physics with the Force Concept Inventory (Hestenes, et al., 1992), and the more recent Geoscience Concept Inventory (Libarkin and Anderson, 2005). To address this project effectively, one must turn also to the issue of how, and when, these concepts are being taught in today’s science classrooms. While most earth science texts have at least a chapter on the atmosphere, is this topic being given the attention that it merits, at a national level? Do science teachers themselves know enough about weather and climate to expose their students to full advantage? These are all worthwhile questions to ask.

66

Given the apparent success of guided-inquiry materials in addressing cloud formation, similar exercises should be developed and tested for the teaching of circulation, heat budgets, greenhouse warming, and other atmospheric applications. The use of drawing as a pedagogical tool (as discussed by Gobert, 2005) seems well suited to the topic of weather, and while drawings were used here to facilitate interviews, no methodical process was undertaken to assess their efficacy. Finally, given the potential of the atmosphere to support the teaching of physical principles in a systems-based format, further work should be done to determine how frequently science teachers actually use atmospheric models in their teaching, and to develop tools that encourage the creation of correct mental models in the learning process. Understanding weather, rather like understanding the physics of motion, entails the matching of examples from casual experience with complex and occasionally counterintuitive principles. If these matches can be made correctly, the sky can be a powerful tool for the science teacher.

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BIBLOGRAPHY Aron, R. H., Francek, M.A., Nelson, B.D., and Bisard, W.J., 1994, Atmospheric Misconceptions. The Science Teacher, January 1994: p. 31-33 Bar, V., 1989, Children’s Views About the Water Cycle. Science Education 73(4): p. 481-500 Bar, V., and Travis, A., 1991, Children’s Views Concerning Phase Changes. Journal of Research in Science Teaching, 28: 363-382 Bar, V, and Galili, I., 1994, Stages of Children’s Views About Evaporation. International Journal of Science Education, 16: p. 157-174 Ben-zvi-Assaraf, O., 2005, A Study of Junior High Students’ Perceptions of the Water Cycle. Journal of Geoscience Education, 53(4) 366-373 Ben-zvi-Assaraf, O., 2005, The Development of System Thinking Skills in the Context of Earth System Education. Journal of Research in Science Teaching, 42(5) 147-158 Brown, D., 1992, Using Examples and Analogies to Remediate Misconceptions in Physics: Factors influencing conceptual change. Journal of Research in Science Teaching, 29(1) 17-34 Byrnes, J., 2000, Cognitive development and learning in instructional contexts. (2nd Ed.) New York: Allyn and Bacon Colardarci, T., Cobb, C., Minium, E., and Clarke, R., 2004, Fundamentals of Statistical Reasoning in Education. New York: Wiley diSessa, A., & Sherin, B., 1998, What changes in conceptual change? International Journal of Science Education, 20(10) 1155-1191 Dove, J.E., 1999, Exploring a Hydrological Concept Through Children’s Drawing. International Journal of Science Education, 21(5) 485-497 Dove, J., 1998, Alternative Conceptions About Weather. The School Science Review, 79(289) 65-69

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Ewing, M.S., 1994, Water Literacy in College Freshmen. Journal of Environmental Education, 25(4), 36-40 Gobert, J.D., 2005 The Effects of Different Learning Tasks on Model-Building in PlateTectonics. Journal of Geoscience Education, 53(4) 444-455 Gopal, H., Kleinsmidt, J., and Case, J., 2004 An Investigation of Tertiary Students’ Understanding of Evaporation, Condensation, and Vapor Pressure. International Journal of Science Education, 26(13) 1597-1620 Haladyna, T. M., 1992, The Effectiveness of Several Multiple-Choice Formats. Applied Measurement in Education, 5(1) 73-88 Henriques, L., 2002, Children’s Ideas About Weather: A review of the Literature. School Science and Mathematics, 102(5) 202-215 Hestenes, D., Wells, M., and Swackhamer, G., 1992 Force Concept Inventory. The Physics Teacher, vol. 30, 141-158 Johnson, P., 1998, Children’s Understanding of Changes of State Involving the Gas State. International Journal of Science Education, 20(6) 695-709 Learning Results, 1997, Sections E-F, Maine Department of Education, 23 State House Station, Augusta, Maine 04333 www.maine.gov/education/lres/lres.htm Libarkin, J., and Anderson, S., 2005, Assessment of Learning in Entry-Level Geoscience Courses: Results from the Geoscience Concept Inventory. Journal of Geoscience Education, 53(4) 394-401 Mayer, V.J., 1995, Using the Earth System for Integrating the Science Curriculum. Science Education, 79(4) 375-391 Murphy, J.G., 2005, Demonstrating Climate Change and the Water Cycle to Fifth Grade Students. American Geophysical Union, Fall Meeting 2005, abstract #ED53A-0325 Posner, G., Strike, K., and Hewson, P., 1982, Accommodation of a Scientific Conception: Toward a Theory of Conceptual Change. Science Education, 66(2) 211-227 Rennie, L, 1995, Children’s Choice of Drawings to Communicate their Ideas About Technology. Research in Science Education, 25 239-252 69

Resnick, Lauren B., 1987, Learning in School and Out. The Educational Researcher, December 1987 p. 13-19 Taber, K.S., 1998, An Alternative Conceptual Framework from Chemistry Education. International Journal of Science Education, 20(5) 597-608

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APPENDICES

71

APPENDIX A: THE WATER CYCLE: A SURVEY Part 1: Please read all of the following questions, and answer to the best of your ability. Feel free to circle more than one answer, if you feel that multiple explanations apply. 1. In elevated regions, clouds frequently appear near the peaks of mountains, even when it is clear elsewhere. Choose the answers below that best explain why this happens. a. Evaporation of snow from mountain peaks b. Condensation of water vapor from the air c. A drop in pressure d. A drop in temperature 2. Fog may be formed by which circumstances? a. Warm air moving over cold water. b. Warm air moving over warm water. c. Very cold air moving over cold water. d. A cool summer evening in a plowed field. 3. Circle any answers that might correctly describe the visible components of a cloud. a. Water vapor b. Ice crystals c. Water droplets d. Smoke 4. When water vapor is condensed into a liquid, which of the following are true? a. Heat energy is absorbed by the water b. Heat energy is released by the water 5. Which of the following answers are true regarding the states of water? a. Water can go directly from vapor to a solid state. b. Water must pass through a liquid state before evaporating c. Water is always a solid below 32°F (0°C) d. Water may exist in two or more states simultaneously. 6. As water molecules evaporate, their __________ increases. a. Speed b. Kinetic energy c. Potential energy d. Size

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Part 2: Please provide brief written answers to the following questions. Use the back of the last page for additional space, if needed. 7. Seattle, Washington can expect upwards of 200 days of rain annually, while Spokane, only 250 miles to the east, is very dry. What might explain this?

8. The Gulf of Maine is famous for its cold waters and frequent fog. What would you expect to be the foggiest month of the year, and why?

9. Radio weatherman Lou McNally concludes a broadcast by stating that “the relative humidity is 85 per cent”. What does this figure mean?

10. A common field treatment for hyperthermia (heat stroke) calls for spraying the patients with water, and fanning them until they start to cool off. Why is this effective?

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APPENDIX B: STATISTICAL TEST DATA FOR SURVEYS Table B.1. One-Way ANOVA of Total Pre-Test Scores

Groups SEA 102 Spring 102 Fall

Count 42 39 34

Variation Between Within

SS 18.9378 634.7492

Sum 349 292 285

df 2 112

Average 8.3095 7.4872 8.3824

Variance 6.0238 5.4669 5.4554

MS 9.4689 5.6674

F 1.6708

74

P-value 0.1928

F crit 3.0773

Table B.2. Dependent Samples t-tests (alpha = .05) of ERS 102 Pre/Post Data

Question 1 t-Test: Paired Two Sample for Means Spring 1 Pre vs. Post Variable 1 Mean 1.3846 Variance 0.8745 Observations 39 Pearson Correlation -0.05094 Hypothesized Mean Difference 0 Df 38 t Stat -1.9356 P(T