What is the difference between a manipulated variable and controlled variable?

in science. [:What is the difference between a manipulated variable and controlled variable?
In an experiment, variables are all those things that might change and because of that might change the results of your experiment.





For example if you were studying the evaporation of water from a beaker, some of the things that might affect the rate of evaporation would be:





wind or air currents in the room


temperature of the water


humidity of the air


surface area of the water





Usually in such an experiment you are trying to study one of the variables to understand how the result changes if that variable changes.


This is the manipulated variable - the one you are changing or manipulating, and watching how the results change when you change the variable. For instance, in the experiment above, if you are studying the effect of surface area on evaporation, you might run one trial with the beaker fully covered, then next time cover it 90% of the way, then 80%, 70% etc. Then you could read your data and see how the change in surface area affected the evaporation rate.





But in order to be sure that the change in results are strictly due to the changing surface area, you would need to make sure that the other variables are controlled, or kept constant. So you would want to make sure that the room temperature, humidity, and water temperature don't change. These are the controlled variables.





I hope this helps