A first class lever is like a teeter-totter or see-saw. One end will lift an
object (child) up just as far as the other end is pushed down.
                      

  Scissors are made up of two class 1 levers and are used for cutting a variety of things.

A first class lever is resistance then the fulcrum and last but not least the input force it could also be input force fulcrum and then resistance. A teeter-totter you sitting on one end would be the input force the bar in the middle is the fulcrum and the kid on the other end is the resistance force.

Click here for second class levers.