What is a fair test?
Lets see who can copy down a list of words first. But wait - each student will receive a different size and style of paper, as well as a different size, shape, and color of pencil. It didn't take long for the students to see that our test was not fair.
It is important for an experiment to be a fair test. You conduct a fair test by making sure that you change one factor at a time while keeping all other conditions the same. To insure that your experiment is a fair test, you must change only one factor at a time while keeping all other conditions the same. Scientists call the changing factors in an experiment variables and those that stay the same constants.
Testing support shapes
Question: Will a square shape support more mass than an arch shape?
Variable: The shape of the index card
Constants: Amount of plastercine supports and placement, material and size of index cards, testing surface, weight increments (increasing by the same amount in the same order for each shape).