Quick Scoop

The controlled variable in an experiment is any factor you keep the same throughout the test so it does not affect the result. It helps make sure only the independent variable is causing the change you observe.

For example, if you are testing how sunlight affects plant growth, things like water, soil, pot size, and temperature are controlled variables because they stay constant. This is the standard definition used in science references and experiment guides.

Simple example

  • Independent variable: amount of sunlight.
  • Dependent variable: plant growth.
  • Controlled variables: same water, same soil, same temperature, same pot size.

In short: a controlled variable is a “keep it the same” factor.

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