1. Experimental Design
Pre-AP Biology

2. Bell Work
Judy observes her two potted plants. One has grown significantly bigger and fuller than the other. Judy wants to see if it is caused by the amount of sunlight that they receive. She plants two different flowers using the same bag of potting soil. She waters them both at the same time each day. She places one in direct sunlight and the other in indirect sunlight.
1. What did Judy do wrong in her experiment?
2. What did Judy do right in her experiment?
3. What would you do differently?

3. Science A way of learning about the natural world
Includes all of the knowledge gained by exploring the natural world
This knowledge is always growing and changing as scientists ask new questions and explore new ideas

4. Scientific Inquiry
Scientific: Of or relating to the practice of science
Inquiry: A close examination of a matter in a search for information or truth
Scientific Inquiry: The ways in which scientists explore the natural world

5. How Does Scientific Inquiry Work?
Scientific Method:
Make observations and/or inferences
Ask questions
Develop hypotheses
Design experiments
Make measurements
Collect data
Interpret data
Draw conclusions
Communicate

6. Make Observations and Inferences
Observation: Using one or more of your senses to collect data
Inference: An interpretation of an observation that is based on evidence or prior knowledge
Data: Facts, figures and other evidence gathered through observation

7. Hypothesis

8. Hypothesis Proposed explanation based on limited evidence as a starting point for further investigation

9. Experiment

10. Experiment A scientific procedure that answers a question or solves a problem

11. Designing an experiment to test a hypothesis
After you state your hypothesis, you must design an experiment to test it.
You figure out a way to test whether the hypothesis is supported.
Control group– nothing changed
Experimental group – one variable changed
The outcome must be measurable (quantifiable).
Record and analyze data.

12. Independent Variable: Dependent Variable: Controlled Variables:

13. Independent Variable: factor that you want to test or manipulate (CAUSE) Dependent Variable: factor you observe or measure during the experiment (EFFECT) Controlled Variables: factors that are the same for all groups; must be kept the same so that effect of independent variable can be seen.

14. Variables
Does the height at which a ball is dropped affect the bounce height of the ball?
Independent variable:

15. Variables
Does the height at which a ball is dropped affect the bounce height of the ball?
Independent variable: Drop height
We know the height of the ball drop; we control this.

16. Variables
Does the height at which a ball is dropped affect the bounce height of the ball?
Independent variable: Drop height
We know the height of the ball drop; we control this.
Dependent variable:

17. Variables
Does the height at which a ball is dropped affect the bounce height of the ball?
Independent variable: Drop height
We know the height of the ball drop; we control this.
Dependent variable: Bounce height
The bounce height depends on the drop height. It is what we measure.

18. Variables Does feeding a dog a high-calorie diet lead to weight gain?
Independent variable:

19. Variables Does feeding a dog a high-calorie diet lead to weight gain?
Independent variable: Calories in diet
We know what we will feed the dog.

20. Variables Does feeding a dog a high-calorie diet lead to weight gain?
Independent variable: Calories in diet
We know what we will feed the dog.
Dependent variable:

21. Variables Does feeding a dog a high-calorie diet lead to weight gain?
Independent variable: Calories in diet
We know what we will feed the dog.
Dependent variable: Dog’s weight
We don’t know how the weight will change before we start. It is what we measure.

22. Variables Does taking a weight loss supplement lead to weight loss?
Independent variable:

23. Variables Does taking a weight loss supplement lead to weight loss?
Independent variable: Weight loss supplement
We control whether we take the weight loss supplement.

24. Variables Does taking a weight loss supplement lead to weight loss?
Independent variable: Weight loss supplement
We control whether we take the weight loss supplement.
Dependent variable:

25. Variables Does taking a weight loss supplement lead to weight loss?
Independent variable: Weight loss supplement
We control whether we take the weight loss supplement.
Dependent variable: Weight
We don’t know whether we will lose weight until we take the supplement. It is what we measure.

26. Variables
Do cancer cells stop replicating when exposed to an experimental cancer drug?
Independent variable:

27. Variables
Do cancer cells stop replicating when exposed to an experimental cancer drug?
Independent variable: Cancer drug
We control whether we expose the cells to the cancer drug.

28. Variables
Do cancer cells stop replicating when exposed to an experimental cancer drug?
Independent variable: Cancer drug
We control whether we expose the cells to the cancer drug.
Dependent variable:

29. Variables
Do cancer cells stop replicating when exposed to an experimental cancer drug?
Independent variable: Cancer drug
We control whether we expose the cells to the cancer drug.
Dependent variable: Replication of cancer cells
We don’t know until we expose the cells to the treatment whether they will stop replicating. It is what we measure.

30. Control Group: Experimental Group:

31. Control Group: group that does NOT receive the independent variable; is not tested on Experimental Group: group that DOES receive the independent variable; is tested on

32. Designing a Controlled Experiment
An experiment in which all of the variables except for one are remain the same
An experiment that is designed to compare an experimental group with a control group.
Ideally, a control group and an experimental group differ in only one variable.
Control group serves as a comparison to measure against

33. Controlled Experiment
A drug manufacturer is testing a new drug to treat gout. An investigator dispenses a placebo (sugar pills containing no drug) to one group. The other group receives pills containing the actual drug.
Which group is the control group?
Which group is the experimental group?

34. Constants
Constant: a variable that does not change for the duration of an experiment; a value that remains the same
Example:
Ball being dropped from different heights - Same ball is used every time (remains constant)

35. Interpreting Data
You do the experiment using the method you came up with and record the results.
After the data are collected, they must be organized and interpreted
Create data tables, graphs to represent data
Perform calculations that will determine what results mean (averages, percentages, totals)
Identify possible sources of errors

36. Conclusion

37. Conclusion Results of the experiment

38. Drawing Conclusions
After you have organized and interpreted your data, you must draw a conclusion.
You need to decide if the data support your original hypothesis.

39. Communicating
Scientists must communicate their findings to other scientists.
This contributes to the growth of the body of scientific knowledge.

40. Scientific Theories
Scientific Theory: A well-tested concept that explains a wide range of observations.
A theory is based on thousands of experiments done by different scientists.
A theory is much broader in scope than a hypothesis.
Theories only become widely accepted in science if they are supported by an accumulation of extensive and varied evidence.
Future testing may prove a theory to be incorrect.

41. Claims, Evidence and Reasoning (CER)

42. Claims, Evidence and Reasoning (CER)
My dad’s an alien
CER Infomercial

43. Claim Statement that answers your original question
Usually one sentence in length
Must be accurate, specific, and completely answer the question
Clear: Does not use vague words such as “they”, “it”, or “stuff”
Concise: To the point, with no unnecessary words (“I think”, “Based on my lab”)

44. Claim
Examples?

45. Claim Examples? Smoking cigarettes leads to lung cancer.
Eating dark chocolate promotes heart health.
Consuming caffeine leads to high blood pressure.

46. Evidence Scientific data that supports your claim
Evidence must be sufficient and relevant to your claim. Not all data is considered evidence!
May be data generated from a lab, or may come from trusted sources (textbook, notes, websites, etc.)
The more evidence you have, the better able you are to prove your claim.
Example: According to epidemiological studies, lung cancer prevalence is higher in smokers than in nonsmokers. In vitro (laboratory) studies have demonstrated that exposing cells to substances in cigarettes leads cells to mutate.

47. Evidence
Examples?

48. Evidence
Examples? According to epidemiological studies, lung cancer prevalence is higher in smokers than in nonsmokers. In vitro (laboratory) studies have demonstrated that exposure of cells to substances in cigarettes leads to mutations.

49. Reasoning
Explanation that connects your claim to the evidence that supports it
Shows why the data you chose counts as evidence by using appropriate and sufficient scientific principles
Acts as the “conclusion” of your experiment
Shows a detailed understanding of the scientific principles involved and uses correct science vocabulary
At least a few sentences in length

50. Lab Report Guidelines I. Title II. Introduction
III. Materials and Procedures
IV. Results/Data Collection/Analysis
V. Discussion/Conclusion
VI. Literature Citation
VII. Questions

51. Lab Report Guidelines: Title
Primary topic dealt with during the experimentation.
Clear and concise; avoid extra words

52. Lab Report Guidelines: Introduction
a. Background information that will help them understand the experiment that you have conducted. Important terms should be defined in the section.
b. Purpose of the lab and should be clearly stated in the introduction.
c. Hypothesis – a testable hypothesis should be included, written in an if-then format.

53. Lab Report Guidelines: Materials & Procedures
A complete listing of the materials and supplies that were used to conduct the experiment should be included in this portion of the report.
In this section of the report you should present the exact steps that were followed in your experiment.
Clearly identify the control, variables and the measurement techniques used.

54. Lab Report Guidelines: Results/Data Collection/Analysis
All of the data that was collected during the experiment should be presented in a data table or tables.
Additionally, a graph of the data should be included in this section.
Make sure that the graph is appropriately titled and axes labeled. Include a legend if necessary.

55. Lab Report Guidelines: Discussion/Conclusions
This portion of the report is used to clearly explain whether the results support or refute the hypothesis being tested.
Explain what your findings mean and what conclusions you can draw from the data.
Sources of error and suggestions for improvement should be included in this section.

56. Lab Report Guidelines: Literature Citation
If any of the information included in your lab write up was taken from a published lab activity, you should include a citation of the source.
The source(s) used should be cited within your lab write-up (especially in the introduction section) using scientific citation. Example: (College Board, 2001).

57. Lab Report Guidelines: Question
The discussion questions found throughout the laboratory should be written and answered in this section.