What are the differences between independent dependent and control variables?

Answer 1

Independent variables are things we cannot control. Like time, even though Einstein has shown that it is relative, I cannot make time go faster or slower in my world. So time is an independent variable for most (almost all) situations. It can also be thought of as the quantity that is being measured.

Dependent variables can be changed/manipulated by the experimenter. Lets say you want to investigate volume of a gas as compared to the pressure. you might be able to change the pressure (that is what Robert Boyle did) and then measure the volume as it changes.

Control variables -- sometimes a topic has more than just two variables affecting the outcome, so you 'control' or keep one or more of these variables constant (the same) during the experiment so that it does not effect the outcome. Look at the pressure/volume thing. Boyle realized that the amount of gas could not be allowed to change nor could the temperature. Both of these would effect the outcome. So he kept those constant. He made them control variables so the could be ignored.