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Control Variable

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
RaceChildren.png
  • 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 experiment would not be a fair test if variables were not controlled.
Experiment: Does light affect cress growth? Controls
Cress.png
  • 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.

Key Stage 3

Meaning

Control Variables are all the conditions of an experimentt that are kept the same.

About Control Variables

Changing more than one variable in an experiment makes it impossible to tell which variable caused the results.
Control Variables ensure that only the Independent Variable could be responsible for a change in the Dependent Variable.
Control Variables make sure an experiment is a fair test.

Key Stage 4

Meaning

Control Variables are all the conditions of an experimentt that are kept the same.

About Control Variables

Changing more than one variable in an experiment makes it impossible to tell which variable caused the results.
Control Variables ensure that only the Independent Variable could be responsible for a change in the Dependent Variable.
Control Variables make sure an experiment a fair test and that the results are valid.

References

AQA

Control variables, page 10, GCSE Biology, CGP, AQA
Control variables, page 10, GCSE Chemistry, CGP, AQA
Control variables, page 10, GCSE Combined Science Trilogy; Biology, CGP, AQA
Control variables, page 10, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Control variables, page 144, GCSE Chemistry, Hodder, AQA
Control variables, page 241, GCSE Combined Science Trilogy 1, Hodder, AQA
Control variables, page 4, GCSE Combined Science; The Revision Guide, CGP, AQA
Control variables, page 4, GCSE Physics; The Revision Guide, CGP, AQA
Control variables, page 5, GCSE Chemistry; The Revision Guide, CGP, AQA
Control variables, pages 17, 178, GCSE Physics, Hodder, AQA
Control variables, pages 253, GCSE Combined Science Trilogy 2, Hodder, AQA

Edexcel

Control variables, page 10, GCSE Biology, CGP, Edexcel
Control variables, page 10, GCSE Chemistry, CGP, Edexcel
Control variables, page 10, GCSE Physics, CGP, Edexcel
Control variables, page 5, GCSE Biology; The Revision Guide, CGP, Edexcel
Control variables, page 5, GCSE Chemistry; The Revision Guide, CGP, Edexcel
Control variables, page 5, GCSE Physics; The Revision Guide, CGP, Edexcel

OCR

Control variables, page 4, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Control variables, page 5, Gateway GCSE Biology; The Revision Guide, CGP, OCR
Control variables, page 5, GCSE Chemistry; The Revision Guide, CGP, OCR Gateway
Control variables, page 8 , Gateway GCSE Biology, Oxford, OCR
Control variables, pages 8, Gateway GCSE Physics, Oxford, OCR