Variables: Independent, Dependent and Controlled

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Background: When conducting experiments, one needs to deal with variables, those factors or elements that are likely to vary or change. A typical study has an independent variable and a dependent variable.

 

The independent (or manipulated) variable is something that the experimenter purposely changes or varies over the course of the investigation. The dependent (or responding) variable is the one that is observed and likely changes in response to the independent variable.

 

For example, a student might change the position of a plane’s wing to see how it affects the average speed of a model plane. The wing position would be the independent variable- because the student purposely changes its location. The average speed would be the dependent variable since the average speed would depend on the location of the wing.

Independent Variable = Wing Position

Dependent Variable = Average Speed

 

When conducting an experiment, all other variables must be kept the same throughout the investigation; they should be controlled. The variables that are not changed are called controlled variables.

 

Asking Testable Questions

Making  Tables and Graphs