VARIABLES
A variable is something that can change. In mathematics, a variable is an unknown number, which we usually represent by 'x'. However, in science, the word 'variable' has a slightly different use when doing an experiment:
Variables are the factors in an experiment which can change the outcome.
There are three kinds of variables . . .
Independent Variable
This is the variable you are testing, or manipulating.
In our experiment, the independent variable was the hours spent studying.
We hoped that by changing the number of hours, we would see a change in the math mark.
Dependent Variable
This is the variable you are measuring.
In our example, for each of the different number of hours spent studying we will measure how much the Math mark changed. The amount of change in the mark would be the dependent variable.
Controlled Variables
These are variables that could affect the outcome of the experiment, which you make the same each time.
In our example we might want to pick people who usually don't study for a Math test, so we could be sure that any studying they do will have some sort of effect.
In addition, we would want to control these other variables (by making them the same for each person) so that we are sure that they didn't cause the change in the mark:
- The environment of the study spot (sounds, temperature, etc.)
- The math ability of the people tested.
- The material being studied.
- The method used to study.
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