The visitor swings a small magnet onto a steel collar attached to a heavy pendulum hung from the ceiling. Because of the weak magnet, the visitor learns that only by pulling in time with the swing of the pendulum (in resonance), can the pendulum be moved. Two magnets are tied to the fence at 90 degrees to each other so the users, if they cooperate, can alter the pattern in which the pendulum swings (circle, ellipse, line, etc.).