Science Assessment ~ Topics ~ Control of Variables ~ Misconception CVM009

In order to determine whether a certain variable has an effect on the outcome, one must vary ALL variables at the same time (Tschirgi 1980).

Items that test for misconception CVM009 in this project (Original Project) and key idea (If more than one variable changes a…)
Item ID Number	Item Description	How Often the Misconception was Chosen
CV001003	A carts and ramp experiment in which the weight of the carts is varied and the height of the ramp is held constant could tell you the effect of the weight of the cart on the cart's speed.	27%
CV006003	An experiment in which the amount of bleach and the size of a stain on a shirt were held constant, and the type of bleach varied, could tell you which of two bleaches was better at removing stains.	13%
CV024005	An experiment in which variable X is allowed to vary and variables Y and Z are held constant could tell you if variable X has an effect on the result of the experiment.	11%
CV004003	An experiment in which the number of fish in a series of fish bowls is held constant and the temperature of the water in the fish bowls is varied could tell you the effect that water temperature has on the behavior of goldfish.	9%
CV002003	An experiment in which the amount of sunlight is varied and the minerals in the plant's water is held constant could tell you the effect of light on plant growth.	5%