Cause and Effect


Science  Fair Projects can be fun if you remember a few rules, such as:

1. Your project should be a cause/effect investigation.

2. In this type of investigation you only want two variables to change and all the other variables are kept constant.

So what do these two rules mean? The easiest way to explain is to use an example investigation.

Purpose: To determine how the amount of water in a container affects the sound produced when the container is tapped.

  • The change in sound (effect) is caused by a change in the volume of water.
  • The cause (independent variable) is a variable that you purposely change. The variable that responds to this change is the effect (dependent variable).
  • The problem for the investigation identifies  the cause (independent variable) and effect (dependent variable).
  • For example: How does the volume of water (cause) in a container affect the sound produced (effect) when the container is tapped?
  • Controlled variables include, the type of container, the type of water, and the type of tapper used.


contest11The two scientists in the photo designed an interesting experiment to discover the relationship between water volume in a container and the sound produced when the container is tapped. For a step-by-step procedure as well as the conclusion for their tests, see ZEE AND BOO.

For more science fair project ideas, see Janice VanCleave’sGuide to More of the Best Science Fair Projects.