What is an independent variable?

A variable is a factor in an experiment that can be changed.

When you set up an experiment in the correct way you need to think about control, independent and dependent variables.

What is an independent variable?

The independent variable is the factor changed in an experiment. There is usually only one independent variable as otherwise it’s hard to know which variable has caused the change.

What is a dependent variable?

The dependent variable is the variable measured in an experiment. It depends on the independent variable!

What is a control variable?

Control variables are variables that must be kept the same in an experiment.

Usually only one variable is measured and an experiment investigates how changing the independent variable affects the dependent variable.

Experiment ideas for learning about setting up a fair test

Investigating the effect of exercise on heart rate

If you wanted to investigate the effect of exercise on heart rate the variables would be as follows

Control variables

Same person exercising

Same method used to measure heart rate.

Independent variable

Type of exercise or no exercise.

Dependent variable

Heart rate

Investigating the effect of viscosity of a liquid on flow rate

If you wanted to investigate how the thickness of a liquid affects it’s flow rate the variables would be as follows.

Control variables

Gradient of ramp

Distance travelled by each liquid

Amount of each liquid used

Independent variable

Liquid used

Dependent variable

Time taken for each liquid to travel a set distance

Last Updated on March 3, 2022 by Emma Vanstone