Step 2:

Variable are the things that change or could be changed in the experiment. There are 3 types of variables: independent, dependent and control variables.
​
  • independent variable: what YOU are changing ​(change or test only ONE)
  • dependent variable: what you are trying to measure
  • controlled variable: things that stay the same in the experiment, keep the experiment fair

Example Experiment:

If your purpose question as:
"Which brand of bubble gum keeps its flavor longest?" 

The variables would be:
  • independent variable: different brands of bubble gum
  • dependent variable: the amount of time the flavor last
  • controlled variable: same amount of gum, all sugar free gum, all the same flavor of gum, and all gum that comes in a stick (not cubes or balls).
Need more help?
​
Here is a video that goes over the three types of  variables: independent, control, and dependent variables.