Define the terms independent and dependent variable.
The independent variable in an experiment is the variable that YOU change in order to affect the dependent variable. The dependent variable is what is being measured, or what is being affected.
For example, If you are testing how the amount of time you leave a sponge in a bowl of water affects the amount of water absorbed, then the amount of time you leave the sponge in is the independent variable, and the amount of water absorbed is the dependent variable. An easy way to remember it is that the dependent variable all DEPENDS on the independent variable (CHANGE)