Simple Yet Helpful
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A waterwheel, like this one, is an example of a wheel and axle. In the past, people used waterwheels to power mills.
© iStockphoto.com/Photogrape
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A long time ago, when our clothes got dirty, we had to wash them by hand. This work took a lot of energy. Today we have washing machines to wash our clothes. Machines make our lives easier!
Some machines have many parts. For example, the cars, buses, and trains that take us where we need to go have lots of parts. Machines with many parts are called compound machines or complex machines. Other machines are made of just a few parts. These are called simple machines. Like other machines, these machines make our lives easier. Levers, pulleys, and wedges are just a few kinds of simple machines.
