A simple machine is a device used to assist people in getting work done faster and easier. Scientifically, work is known as using force upon an object in order to transport it to a new location. Pushing, pulling, and lifting are all common forms of work. Simple machines can used to simplify these actions, making it easier for the laborer to complete the task.
Pulleys, levers, wedges, screws, wheels and axles, and inclined planes are all examples of simple machines. They can all help people do work in some form. For example, a gardener must remove the weeds from his garden on a regular basis. He could use his bare hands, but using a shovel, a lever tool, will allow the job to be done with less effort. In another example, inclined planes are useful in helping movers load furniture into trucks. By using a ramp, they are able to roll the large items into the truck on wheels rather than lift them.
Here is a list of links to lesson plans and resources for teaching students about simple machines.