Turn over the Wheel Timer and watch the liquid turn the wheels as it drips down. It takes approximately two to three minutes (depending on room temperature) to completely empty into the lower portion. Great prop to keep on a science table for the children to tip, turn and watch as the liquid turns the wheel. Wheel timer can also be used for teacher or child stress/relaxation, quiet time toy, refocusing prop, anxiety prop, or a timer. The Wheel Liquid Timer is 5" tall.