The control is the base experiment for comparison with other trials of the experiment. A constant is a quantity that does not change.
Contrast this with an experimental variable which is the part of an experiment that is affected by the experiment.
What is a constant variable in an experiment. A controlled variable is a variable that could change but that the experimenter intentionally keeps constant in order to more clearly isolate the relationship between the independent variable and the dependent variable. Although you can measure a constant you either cannot alter it during an experiment or else you choose not to change it. True constants and control constants.
An example is the water pressure for a faucet when measuring the amount of water released when the faucet is opened to various increments. A constant variable normally called a controlled variable is the term for a variable that remains constant throughout an experiment though other variables may change. There are two main types of constants you may encounter in experiments.
The dependent variable is the part of the experiment that reacts to the independent variable. For example an experiment examining the relationship between how much sunlight plants receive independent variable and how tall they grow dependent variable should make sure none of the other factors change.