Difference between revisions of "Control Variable"

Revision as of 10:22, 20 August 2018

Key Stage 2

Meaning

A control variable is something which is kept the same in an experiment to make it a fair test.

About Control Variables

Changing more than one thing in an experiment can affect the results.

If you do not have control variables it is not a fair test.

Examples

This race would not be a fair test if variables were not controlled.
Investigation: Who is the fastest?	Controls
	Everyone starts from the same starting line. Everyone finishes at the same point. Everyone wears the same kind of shoes. Everyone has to run on the grass.

This race would not be a fair test if variables were not controlled.
Experiment: Does light affect cress growth?	Controls
	All cress gets the same amount of water. All cress is kept at the same temperature. All cress has the same amount of soil.

If you want to know how plants grow differently depending on the light, you should make sure they are all watered the same, have the same soil and are kept at the same temperature.

@@ Line 28: / Line 28: @@
 |[[File:Cress.png|center|300px]]
 |
-*Everyone starts from the same starting line.
+*All cress gets the same amount of water.
-*Everyone finishes at the same point.
+*All cress is kept at the same temperature.
-*Everyone wears the same kind of shoes.
+*All cress has the same amount of soil.
-*Everyone has to run on the grass.
 |}
 If you want to know how plants grow differently depending on the light, you should make sure they are all watered the same, have the same soil and are kept at the same temperature.