This inquiry activity should be done before students have studied the operation of a first-class lever. The activity could be used when discussing simple machines or torque. Although it involves the use of a lever, the activity is not really about simple machines; it is about torque. If students have been taught about levers previously, you may see the “Aha!” moment when they suddenly realize why the sum of the products of mass and distance are equal on each side of the lever. The concept of torque helps them understand why the lever works the way it does.