After developing your hypothesis, the next step in the inquiry process is to design a controlled experiment in order to test your hypothesis. in a controlled experiment, all variables are kept constant except the one that you are testing. the variables you keep the same are called controlled variables. the variable that you change or test is called the manipulated variable. the variable that responds to changes you make is called the responding variable. a. how would you design a controlled experiment to test the hypothesis you made about the volume of a gas? b. what is the manipulated variable in your experiment? c. what is the responding variable in your experiment?