The length of the ramp, the speed and weight of a ball
Explanation:
A controlled experiment needs to be done with constant values and one variable value. According to this experiment, the only variable value is<u> the angle of the incline</u>. And the student must hold constant the <u>length of the ramp</u> where each ball rolls. <u>The ball speed</u> and its<u> weigh</u>t.
By doing this, He can determine how far a ball rolls over the same length ramp, depending on the variable angle of the incline.