Variable

Key Stage 2

Meaning

A variable is something that you can change, keep the same, or measure/observe in an investigation.

About Variables

There are three types of variable.

• Independent Variable: The thing you choose to change in an investigation.
• Control Variables: The things you keep the same in an investigation to make it a fair test.
• Dependent Variable: The thing you measure or observe in an investigation.

In an experiment or investigation there should only be 1 independent variable. If you change more than one thing at a time, it is not a fair test.

Examples

An investigation to test the claim: All leaves are green.

Oak Leaf	Beech Leaf	Ash Leaf
Maple Leaf	Chestnut Leaf	Variables
		The type of leaf chosen was the independent variable. The colour of the leaves was the dependent variable The experiment was done at the same time of year for every tree because at different times leaves can change colour or fall off. This was a control variable

Results Table	Variables
	The type of food chosen was the independent variable. The colour of the iodine after being added to food was the dependent variable. There are many control variables that should be done. If the food colour was blue or black it might give the wrong result, so all the food should be the same pale colour. Another control variable is the amount of iodine used.

Experiment	Variables
Cress seeds were put in pots with soil with half placed in a dark cupboard and half on a windowsill.	Independent Variable: Where you chose to put the cress seeds. Dependent Variable: The observations of the cress seeds. Control Variable: How long you left them for. They should all be left for the same amount of time or it's not a fair test. Control Variable: How much you watered them. They should both be watered the same amount to make it a fair test.

Key Stage 3

Meaning

A variable is anything which could affect the results of an experiment or that you can change, keep the same, or measure/observe in an investigation.

About Variables

There are three groups of variable in an experiment:

• Independent Variable: The thing you choose to change in an investigation.
• Control Variables: The things you keep the same in an investigation to make it a fair test.
• Dependent Variable: The thing you measure or observe in an investigation.

In an experiment or investigation there should only be 1 independent variable. If you change more than one thing at a time, it is not a fair test.

Key Stage 4

Meaning

A variable is anything which could affect the results of an experiment or that you can change, keep the same, or measure/observe in an investigation.

About Variables

There are three groups of variable in an experiment:

• Independent Variable: The thing you choose to change in an investigation.
• Control Variables: The things you keep the same in an investigation to make it a fair test.
• Dependent Variable: The thing you measure or observe in an investigation.

In an experiment or investigation there should only be 1 independent variable. If you change more than one thing at a time, it is not a fair test.

There are three different types of variable which can be recorded in an experiment:

• Categoric Variable - A variable that changes by category, not by numerical values (eg eye colour, blood type, type of animal.)
• Discrete Variable - A variable which can only be specific values with no numbers in between (eg shoe size, number of people, number of atoms).
• Continuous Variable - A variable which has any possible value (eg height, time, temperature, current).