The Scientific MethodObjectives: 1. Describe the steps scientists use to

investigate a question or problem. 2. Explain each step in the scientific method. 3. Explain the difference between an

experiment and a control setup. Key Terms: fact hypothesis law principle scientific

method theory

Scientific Method 1. Recognize a problem.

(Observation) 2. Make an educated guess

(hypothesis) about the answer.

3. Make a prediction based on your hypothesis.

4. Perform experiments to test predictions.

5. Formulate the simplest general rule that organizes the three main ingredients: hypothesis, prediction, and experimental outcome or modify your hypothesis and start the process again.

Hypothesis In science facts observed by knowledgeable

observers lead to the formation of a hypothesis (educated guess). This is not like saying that the sky is blue. A scientific hypothesis must be testable. You must be able to test for its rightness as well as its wrongness. A hypothesis must also add to our understanding of nature. Once a proper hypothesis has been formulated, testing may begin.

Devising a test for your hypothesis

Identify the variable to be tested. a variable is a single condition, factor, or

step in the process that you wish to prove. 2 main types. manipulated - variable you change responding - variable you observe

Example: you may be testing the rate of photosynthesis in plants. You may want to test the amount of light first. The temperature, soil, plant type and age, amount of watering, etc. should remain the same.

Setup a control A control setup is one where no variable has

been changed. Example: If you are increasing the light

intensity in your experiment, the light intensity in the control setup will remain the same. This is an example of testing for wrongness.

If the variable tested supports your hypothesis, pick another variable. You may want to test temperature next. When all conceivable variables have been checked you are ready to form a theory about the initial observation

Formulation of a Theory A theory is a scientist's best explanation for

an observation. It can only be called a theory, though, after it has been thoroughly been tested. Theories are not fixed. They constantly undergo change. Atomic theory is a classic example of this. As testing methods get better, new information gradually modifies what the theory contains and how it is interpreted. If a theory withstands the test of time it can possibly become a law or a principle.