Scientific Method and Graphing p g
Spontaneous Generation • Living things come from nonliving things • Believed for a very long time • Why would peo...
1668 – Francesco Redi rejected the hypothesis of spontaneous generation with his hypothesis that flies produce maggots
Redi’s Experiment p
Historical Experiments Mid 1700s – John Needham claimed that spontaneous generation could occur under the right conditions
Historical Experiments • Mid 1700s – Larraro Spallanzani improved Needham’s experiment by sealing the flask
Historical Experiments • 1864 – Louis Pasteur settled the spontaneous p generation argument by creating a flask that had a long curved neck allowing air into the flask
The Scientific Method involves a series of steps p that are used to i investigate sti t a natural occurrence.
We will ll take k a closer look at these steps and the terminology you will need to y understand before you start a science project. j t
1. 2. 3. 4. 5. 6. 7. 8.
Steps of the Scientific Method 1. State the Problem/Question: Q Develop a question or problem th t c that can nb be ssolved lv d through thr u h experimentation. p m . Example:
2. Do research about the problem: Do research on your topic of interest. Example:
Do y you remember the next step?
3.Make a Hypothesis yp Predict a possible answer to the problem or question. question E mp Example:
4. Design and perform a Controlled Experiment: A controlled experiment p must test only y __ f factor. The factor that is tested is the ____________. The part of the experiment that contains the variable is called ll d the th _______________. Another part of the experiment is done that is the same in every way except it does not contain the variable. This part of the experiment is called the _________. In a scientific experiment, the control is the group that serves as the standard of comparison. The part of the experiment that does not contain the variable is called the _____________.
Example: What is the factor we want to test? Variable: Experimental Group Group: Control Group: People who do not get the “Miracle Pill”. They take a pill that looks exactly like the “Miracle Miracle Pill Pill”. This is called a Placebo. Placebo How long will your experiment go on for?_____ How many people will be in your experimental group? ______ How many people will be in your control group? _____ What age group of people will participate in your experiment? p ___________ When will the people in your experiment take the Pill the are given?_______________
Why is everything Wh thin in the th experiment xp im nt exactly the same except whether or not th are taking they t kin the th “Mi Miracle cl Pill”?
Independent Variable The independent, independent or manipulated variable, is a factor that’s intentionally varied by the experimenter.
Wh making When ki a graph h the th independent i d d t variable i bl goes on the ______________ .
Example: E l Whether Wh th or nott the th people p p in the experiment p got g the “Mi “Miracle l Pill”
Dependent Variable The dependent dependent, or responding variable, is the factor that may change as a result of changes made in the independent variable. variable The dependent variable always goes on the Y-axis. Example:
5.Collect Data
Data or observations are recorded. Observations can include mathematical measurements, as well ll as observations b i made with the senses or with scientific instruments. instruments Example: The people participating in the experiment p m will fill f out a chart that asks them to evaluate their skin, hair, nails, muscle tone etc. Y will You ill organize i your d data t by b iincluding l di tables, graphs, and photographs.
Results of questions answered by participants ti i t iin experiment i t after ft 30 d days. Experimental Group
Control Group
Does your hair feel lik it did 10 years like ago?
1
0
Do your nails feel 10 years younger?
0
2
Does y your skin look like it did 10 years ago?
1
1
Does your muscle tone feel like it did 10 years ago?
2
1
6. Analyze Results 6 Example: Study the data and determine if their was any major difference in how the Experimental Group felt compared to how the Control Group felt at the end of the experiment.
7. Form a Conclusion: 7 Include a statement that accepts or rejects the hypothesis. Ex mpl : Th Example: The “Mi Miracle l Pill” d doess not work. wor . The h following fo ow ng data:… ata …
8. R 8 Repeat p t th the experiment xp im nt You must p perform the experiment again. You must get the same results again. g If you y d not get the do h same results l again g you y must work on your y experimentall procedure. d Other h scientists must be able to perform f your experiment and d get the same results. g
Put the following steps of the scientific method in the proper order: A. _____ organize and analyze data B _____ State B. St t a hypothesis h th i C. _____ identify the problem D. _____ State conclusion E. _____ design g and carry y out an experiment F. _____ Make observations and record data G. _____ gather information
Think yyou can name all eight steps?
Collect State Experiment the Data Problem/Question and Analyze Data Repeat DoFormulate Research Conclusion the experiment a Hypothesis
Once a scientific hypothesis meets the test of repeated experimentation it becomes a Theory.
A Scientific Law is a statement that summarizes the results of many observations and experiments. experiments Difference between a Law and a Theory? ___________- tells what happens ___________-- our attempt to explain why it happens
Graphing
To study data more easily, science researchers record d laboratory l b t observations bs ti ns and nd measurements in an organized manner. This careful method of organization helps researchers h visualize i li data d t and dh helps l them th reach more accurate conclusions. Three common methods used to record observations: • Bar graphs • Data D t tables t bl • Line graphs
Bar Graphs A bar graph allows the scientist to compare data.
Interpreting a Bar Graph
Data Table The data table is used to record numerical data. The information is organized by arranging observations in columns with appropriate pp p headings.
Year
Amount of Rain (inches)
Bushels of Grain per Acre
1979
13
60
1980
7
50
1981
10
65
1982
9
60
1983
11
70
1984
15
20
1985
12
65
Rearrange the data in the table completing both Columns of the data table provided, so the values of Amount of Rain (inches) are increasing from the top of the table to the bottom.
Amount or Rain (inches)
Bushels of Grain per Acre
Interpreting a Data Table
Line Graph • • • •
A line graph is used to show relationships between 2 variables. One variable, called the independent variable, is placed along the horizontal (bottom) or X X-axis axis. The other variable, the dependent variable, is placed on the vertical (side), or Y axis. The data for the dependent variable depends on the changes in the independent variable.
3.0 3.6 4.0
3.0 3.6 4.0
Timeline of Events Year
Event
1668
Francesco Redi attacks spontaneous generation and disproves it for large organisms
1745
John Needham adds broth to a flask and boils it, lets it cool and waits. Microbes grow and he proposes it as an example of spontaneous generation.
1768
Lazzaro Spallanzani repeats Needham's experiment, but covers the flask after boiling. No growth occurs.
1859
Louis Pasteur's swan-neck flasks show that spontaneous generation does not occur.
1870
Thomas H. Huxley gives his "Biogenesis and Abiogenesis" lecture. The speech offered powerful support for Pasteur's claim to have experimentally disproved spontaneous generation.
1877
John Tyndall publishes his method for fractional sterilization, showing the existence of heat-resistant bacterial spores.
