The Scientific Method:


    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

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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



           Modify your hypothesis and start the process again.

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.

When devising a test for your hypothesis, it is important to identify the variable to be tested.  A variable is a single condition, factor, or step in the process that you wish to prove.  For instance, 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 be the same.   The scientist will also setup a control.  A control setup is one where no variable has been changed.  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.

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.