The lever is one of the six classic simple machines. A simple machine is a mechanical device that changes a force’s direction or magnitude. The other five simple machines are the wheel and axle, the pulley, the inclined plane, the wedge and the screw. Explaining simple machines to kids can be a fun learning experience, especially if you include some demonstrations in the lesson. Click here to see how I built a lever for a demonstration of simple machines for my son’s 3rd grade class.