Fiducia TogetherVariables
The thing you change, the thing you measure, and everything you must hold still.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
The independent variable is what you deliberately change. The dependent variable is what you measure. Control variables are everything else kept the same so the comparison is fair.
Where it applies
Every practical in every science, and in psychology and geography fieldwork.
How it works
A result only means something if the only thing that changed was the independent variable. Any uncontrolled variable gives an alternative explanation, which is what makes a conclusion unsafe.
A control experiment is different from a control variable: it is a run with the independent variable absent, used as a comparison.
How to use it in your work
Name them explicitly using the words independent, dependent and control. Questions award marks for the terminology.
When asked to improve a method, naming an uncontrolled variable and how to control it is almost always available.
Where to get help
Your teacher, your board's specification for the depth required at your tier, and Bitesize for the diagrams. The subject song runs the topics in order.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.