1. The Scientific Method

2. The Process of Science 1. Careful Observation 2. Question
3. Formulate a Hypothesis
4. Make a Prediction (“if-then” statement; assume the hypothesis is correct and predict the result
of a test)
5. Test (collect data)
Experimental group -receives the treatment/condition
Control group -business as usual; does not receive treatment
Independent, dependent and controlled variables
6. Conclusion (if prediction does not occur, then hypothesis is falsified; if prediction occurs, hypothesis is
supported)

3. Question Well defined Testable Measurable Controllable
Reasonable and consistent with existing bodies of knowledge

4. Consider These Questions
Are serial killers evil by nature?
What is the cause of AIDS?
Why is grass green?
What is the best recipe for chocolate chip cookies?
When will the big earth quake hit San Francisco?

5. Hypothesis
Testable
Falsifiable
Written as a statement

6. Which of the following is a useful scientific hypothesis?
Plants absorb water through their leaves as well as their roots.
Mice require calcium for developing strong bones.
Dogs are happy when you feed them steak.
HIV can be transmitted by cat fleas.

7. Tests Have Variables Dependent Independent Controlled
The variable measured, counted, or recorded.
Placed on y-axis of a graph
Independent
What the investigator deliberately varies or manipulates during an experiment.
Chosen because it is thought to affect the dependent variable
Placed on x-axis of graph
Controlled
Variables or factors that are kept equal in all treatments.

8. Identify the D and I variables
Mice are kept at different temperatures for 6 weeks. Percent weight gain is recorded.
A hypothesis proposes that dog weight increases with fewer litter mates.
Seeds are soaked in salt solutions of different concentrations and germination is counted each day.
The diversity of coastal algal species is calculated before and after an oil spill.