What is an experiment?

Once we have identified some suitably small, focussed questions we can then begin to figure out how to find the answers to them. Scientists do this in many ways, but one of the most important ways is by carrying out an experiment.

We can think of an experiment as a process where we control certain things, and find out what effect is caused by changing them. Anything that can be changed in an experiment is called a variable.

The variable to change in the experiment is called the independent variable, because it doesn’t – or shouldn’t – depend on anything else.

The variable to measure in the experiment is called the dependent variable, because we think it will depend on the thing we are changing.

The other variables – things which may affect the dependent variable, but that we do not want to test, are said to be controlled variables. By controlling these variables we make sure that our experiment really is showing us the effect we want to find – that it will be a valid experiment.