AAAS Science Assessment ~ Topics ~ Control of Variables ~ Misconception CVM028

A controlled experiment tests for the effect of variables that are held constant, not the variable that is allowed to change.

Items that test for misconception CVM028
Item ID Number	Item Description	How Often the Misconception was Chosen
CV017002	A controlled experiment involving the behavior of fish in fish bowls, in which the number of fish in the bowls varies and the temperature of the water and the amount of light is held constant, allows you find out the effect of the number of fish on fish behavior.	21%
CV018002	A controlled experiment involving the drying of swimsuit fabric, in which the type of fabric changes but how large a piece of fabric you use and how wet the fabrics are to start with are held constant, can tell you if the type of fabric affects how long it takes the fabrics to dry.	19%
CV019002	A controlled experiment involving the floating of clay boats, in which the shape of the boats varies and the weight of the boats stays the same, can tell you if shape affects the floating of the boats.	19%
CV030001	In an experiment involving three variables (X, Y, and Z) that could affect the outcome of the experiment, changing X and keeping Y and Z constant allows you find out the effect of X on the outcome of the experiment.	16%
CV023005	In an experiment involving two variables (X and Y) that could affect the outcome of the experiment, changing X and keeping Y constant allows you to find out the effect of X on the outcome of the experiment.	14%