[JOAN CARTAN-HANSEN] Simple machines help us make better use of our muscles to do a thing called work. Don't be fooled by the name. Simple machines help create things that are very complex. A simple machine controls the direction of the force or energy we apply. They're very handy because they make many movements and jobs easier to do. Simple machines work either alone or in various combinations. They make up most of the gadgets and mechanical devices we use every day.

The six simple machines are: the lever, the pulley, the wheel and axle, the inclined plane, the wedge and the screw.

The lever is the oldest simple machine. It's probably best described with a see-saw. Every lever - every seesaw - has a fulcrum. That's the point where the seesaw moves. It's right in the middle. The way a lever works is downward motion on one end results in upward motion at the other. Scissors are also a good example of a lever.

Next are pulleys. There are pulleys in cranes and elevators and your fishing pole has a pulley too. A pulley helps you move something up or down. It's a special wheel with a rope around it. When you give the rope a tug the object at the other end can easily be lifted. If you combine several pulleys you can lift something that normally you'd never be able to carry.

The wheel and axle is best described with a good look at the tires of a car or truck. A wheel and axle rotate together. The wheel is locked to a central axle. When one turns, they both turn. The wheel and axle allows you to move the heavy car or truck. Another wheel and axle is a knob on a radio. The most simple of the simple machines is the inclined plane. It's a sloping surface used to lift or help move heavy loads with little effort.

A wheelchair ramp is a good example of an inclined plane. It allows someone to go inside without trudging up the stairs. With an inclined plane, even though you're going a longer distance, it takes less effort to move.

Next is the wedge. It's shaped a little like an inclined plane. Have you ever seen someone chop wood? They're probably using a wedge between the ax and the log to help drive a force into the wood and split it apart.

[chop, chop, chop]

Another simple machine is the screw. Anytime you take a lid off a jar of peanut butter you're using it. A screw is a long incline with a central core and a groove wrapped around it. Every time you screw off the lid from a jar you're seeing a simple machine in action. Screws are also very useful to hold things together. It's hard not to find examples of simple machines. They've been around for thousands of years.

Humans used simple machines to build the great pyramids. We use them every day in cars, school rooms, everywhere. The bottom line is that simple machines are tool to make work easier.

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