Scientific Method

The scientific method can be used in a daily situation. You arrive home late at night, walk up to your

house door, unlock the door, reach in to the light switch just inside the front door.

The light does not come on! Now what?

There are several versions of the scientific method. Some versions have more steps while others may have only a few.

1. Observation/Ask a Question Observation – the process of obtaining

information by using the senses

2. Background Research

Background research is conducted to gain a thorough understanding on the observation. Some examples:

Asking experts Reading books and articles

3. Form a Hypothesis

A hypothesis is an explanation that is based on observations and that can be tested.

A good hypothesis should make logical sense.

4. Conduct an Experiment

Experiments – procedures that are carried out under controlled conditions to discover or test a fact or hypothesis

4. Conduct an Experiment

Variable – the factor that changes in an experiment in order to test a hypothesis

4. Conduct an Experiment

Dependent variable – the variable that is measured by the researcher It relies on the independent variable.

Independent variable – the variable that is manipulated and controlled by the researcher It influences the dependent variable.

4. Conduct an Experiment

Example of a hypothesis: Woodpeckers prefer oak trees over maple trees. Dependent variable

Number of woodpeckers Independent variable

Trees

A good hypothesis has both independent and dependent variables.

4. Conduct an Experiment

The control group is a group of subjects or conditions that is not exposed to any experimental treatment.

The experimental group is the group that is identical to the control group except for one factor and is compared with the control.

4. Conduct an Experiment

Placebo - An inactive substance used as a control in an experiment to determine the effectiveness of a medicinal drug

5. Collect Data/Analyzing Results Data is any piece of information acquired

through observation or experimentation.

Organizing data into tables and graphic illustrations helps scientists analyze the data and explain the data clearly to others.

6. Draw a Conclusion

Scientists determine the results of their experiment by analyzing their data and comparing the outcome of their experiments with their hypothesis (or prediction).

7. Report Results

Scientists publish their results, sometimes in scientific articles, to share what they have learned with other scientists.

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Theory vs. Law

A theory is what one or more hypotheses become once they have been tested many times and is generally accepted as true. Cell theory

All living things are made of cells Cells are the basic units of all life Cells come only from other cells

Theory vs. Law

Law - generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation Law of gravity = 9.8 m/s2