Have you ever used a seesaw at the playground? A seesaw is a kind of simple machine called a lever. A lever is a stiff bar that rests on a special point and helps you lift heavy things.

The point a lever rests on is called the fulcrum. The bar can tip up and down over the fulcrum, like a seesaw tipping over its middle bar. Where you place the fulcrum changes how much lifting help you get.

A lever lets a small push move a big load. When you press down on one end, the other end lifts up. Push down on the long end, and even a little kid can lift a heavy friend on the short end of the seesaw.

Levers are hiding all around your house. A pair of scissors is two levers working together, and a bottle opener pops a cap by tipping over its fulcrum. Even your arm is a lever, with your elbow as the fulcrum.

The farther you are from the fulcrum, the easier the lifting feels. That is why a long crowbar can pry up a heavy rock that your hands alone could never budge. The long bar spreads your push out and makes it stronger.

Levers were one of the first machines people ever used. Long before trucks and cranes, people moved giant stones by resting a long pole on a rock and pushing down on the far end.