Fair Test

Your experiment must be a 'Fair Test'

A 'fair test' situation is vital for an investigation's results to be meaningful.

You therefore have to use the scientific knowledge you have explained to identify all of the variables in your investigation.

Say which one of the variables will be the variable you are going to change - the independent variable and which one you are going to observe changing - the dependent variable.

Then say what variables will need to be controlled (otherwise it will not be a fair test) - using theory to explain why they need controlling and how you are going to do it.

You then need to say how you are going to change your independent variable and by how much (the range over which you will change it).

You need to explain how you found out that was a suitable range to investigate. It may well be your preliminaries that helped you decide on a suitable range!


Remember - your design of a fair test must be linked to your scientific knowledge. (That is what helps you to know what to control - what to change and what to measure).