Independent: The person's running speed
Dependent: The time it takes to run a mile
Constants: The mile.
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The independent variable stands on it's own. It will not change based on the Dependent Variable.
The dependent variable, the time it takes a person to run a mile, will change based on the Independent Variable, the person's running speed.
The constant is the mile. In an experiment, the mile, will stay the same. In each trial, it will stay the same, unlike the data for the independent and dependent variable.