CONTROLS

     You must have a control or controls in your experiment. This means you keep part of your experiment "normal" or "untreated" so that you can compare you "experimental" group to it. For instance, in our "How does changing the pH of the water effect plant growth" project, you would need ot keep some plants that get "normal" or "untreated" water.

    Sometimes it is hard to have a "normal" group. Talk with you teacher, other students, and scientists for ideas on what you control should be. Sometimes you do not have a real control group, but you compare to groups for your results. An example of this would be a project that asked, "What kind of oil produces the most heat energy?" In this project, you would compare the different types of heat energy produced by the different types of oils.

Think of a control(s) for these experiments.
 

What kind of car window tinting is best?

Where is the coolest part of a house?

What type of food do cockroaches prefer?