1. Scientific Method

2. Goal What is the scientific method? Does the scientific method work?
What is not a scientific argument.
Does biology follow the scientific method?

3. What is science? Science is ________.
Medicine: “I have high cholesterol, what should I do?”
Take cholesterol lowering medication.
Consult your astrologer.
Pray to the god Baal and sacrifice a goat.

4. Steps in the Scientific Method
Observation
Hypothesis
_____________
Experiment
Conclusion

5. Everyday Science Scientific Method Car Repair Observation
Engine won’t turn over.
Hypothesis (_________________)
Predict battery is dead.
Test (_______________)
Replace battery.
Observe result
Engine now turns over.
Revise hypothesis?
Not needed.
New test?
Scientific Theory
Cars won’t work without a fully charged battery.

6. Making Spaghetti Sauce
Everyday Science
Scientific Method
Making Spaghetti Sauce
Observation
Spaghetti sauce is made of tomatoes.
Hypothesis (prediction)
Try to make tomato sauce with whole tomatoes.
Test
Heat pot of tomatoes.
Observe result
Taste the sauce – yuck.
Revise hypothesis?
Use tomato sauce and garlic!
New test?
Add garlic, taste - not so bland.
Scientific Theory
The Final Recipe.

7. Observations Gathered through your _________
A scientist notices (wonders about) something in their ______________

8. Observations
An example of a scientific observation might be noticing that many salamanders near a pond have curved, not straight, tails

9. Hypothesis
A suggested solution to (reason for) the problem or observation
An ____________
Must be ________
Sometimes written as If…Then… statements
___________an outcome

10. Hypothesis
An example of a hypothesis might be that the salamanders have curved tails due to a pollutant in the moist soil where they live

11. An Experiment is a _________ set up to test the hypothesis.

12. Variable – factor in the experiment that is being tested

13. Experiment
A good (valid) science experiment tests a single variable that can be measured against a control.

14. Experiment
Controlled experiments are situations where all factors are the same between two test subjects, except for the single __________
______________

15. Experiment The independent variable is the ____________
____________ in the experiment

16. Scientific Experiments Follow Rules
An experimenter ___________
___________
and observes or measures what happens.

17. Variables
Remember, the factor that is changed is known as the _______________________.
The factor that is measured or observed is called the _______________________.
(What “happens” DEPENDS on what the experimenter changed!)

18. What is the Purpose of a Control?
Controls are NOT being tested
Controls are used for COMPARISON

19. Example of Controls & Variables
For example, suppose you want to figure out the fastest route to walk home from school.
You will try several different routes and time how long it takes you to get home by each one.
Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

20. What are the Variables in Your Experiment?
Varying (changing) the route is the independent variable
The time it takes is the dependent variable
Keeping the same walker throughout makes the walker a control variable.

21. One more thing… it is best to make several trials with each independent variable.

22. Valid Experiments
Two groups are required --- the control & experimental groups
There should be only one variable

23. Data Results of the experiment
May be quantitative (numbers) or qualitative

24. Data
Must be organized
Can be organized into charts, tables, or graphs

25. Conclusion
The answer to the hypothesis based on the data obtained from the experiment

26. In order to verify the results, experiments must be retested

27. Theories, Guesses, Laws What does the word “Theory” mean?
“A conjecture; guess” (Webster’s Dictionary)
Is a Theory less than a Law?
“Evolution is a theory, it is not a fact.”
Do Theories “grow up” to be Laws?
“Einstein’s Theory of Relativity”

28. So??????
A successful hypothesis eventually becomes a Scientific Theory.

29. Theories A theory is a highly successful hypothesis.
All hypotheses make predictions.
All theories make predictions.
All theories can be tested.
Result: Any scientific theory is subject to change as our ability to make tests, or make observations of a test’s results, improves with time.

30. Non-scientific Theories
Make no predictions
Un-testable
Can’t be proven

31. Non-scientific Theories
Car won’t work?  Aliens drained the battery.
Spaghetti is bland?  You were meant to eat bland food.
Car won’t work?  Gods must be angry.
Spaghetti is bland?  At the instant of tasting, the tongue is transported to alternate dimension where all flavors are rendered nullified. Happens instantaneously.