The Lever is a simple machine which provides mechanical advantage equal to the distance from the force to the fulcrum divided by the distance from the load to the fulcrum.
There are three classes of levers. A first class lever has the fulcrum located located between the force and the load. When one end of the first class lever rises, the other end falls. A seesaw is a first class lever. A second class lever is a lever in which the load is located between the force and the fulcrum. A second class lever does not change the direction of the force. A wheelbarrow is a second class lever. A third class lever is a lever in which the force is applied between the fulcrum and load. Tweezers are a third class lever.