Machines are ways to make it easier to do work. Many plants and animals have evolved natural machines like arm muscles (a kind of lever) or teeth (a kind of wedge) or a bacteria's flagellum (a kind of screw). Many animals also make machines out of dirt, wood, and stone. People make machines too. There are six different kinds of simple machines. Many of the more complicated machines we use are made of combinations of these six simple ideas.
- Lever (like a can-opener)
- Inclined plane (like a wheelchair ramp)
- Wheel and axle (like a red wagon, or a car)
- Screw (like a corkscrew for wine)
- Wedge (like a knife or a fork)
- Pulley (like a construction crane)