Lever-A lever is a stick that you push down on to lift an object. The purpose of the lever is to make lifting heavy objects easier. Every lever has a fulcrum. The fulcrum is the part of the machine that doesn't move.

Wheel- A wheel helped advance civilization. An example was the chariot. Four wheels and  two axles (a stick in the middle of two wheels) were put together. Then a piece of wood was put on top of them. This was the general way that people made wagons and chariots. The wheel also was able to help make some machines such as  the grindstone.

Pulley- A pulley uses a rope and wheel. It has a round track for the pulley to pull the rope that will pull the object up. The more pulleys used, the less effort is needed.

Inclined plane- It is a slope or a ramp. The inclined plane makes lifting objects easier.

Wedge- A wedge has a shape like an inclined plane. An example is an axe, a knife blade is a wedge, and so is a nail and a sewing needle. The point of a wedge makes an opening, the rest of the wedge is driven in. It makes using a hammer and nail easier. 

Screw- Another simple machine is the screw.  A screw is actually an inclined plane that winds around and around.  Instead of going in a straight line like the inclined plane, a screw turns and moves upward at the same time.