What is controlling manipulating and responding variables?

Controlling Variables are the variables that stay the same.

The Manipulated Variable is the variable that you changed on purpose. There can only be one manipulated variable.

The Responding Variable is the variable that was changed due to the experiment. For example, if you were testing how fast ice melts with differet materials, the responding variable would be the time it took for the ice to melt. Again, there can only be one responding variable.