Machines are instruments made by people to help them to do their work.
Pulleys, ramps and levers are machines.
In class we are using different machines and learning about them.
Look at the photos:
https://picasaweb.google.com/112689455191342219309/MACHINES#
Now play and learn about simple and complex machines:
http://www.edheads.org/activities/simple-machines/index.htm