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When "Hardware Hal" holds a "Simple and Compound Machines Sale" he demonstrates to his assistants the six simple machines: the lever, wedge, inclined plane, pulley, wheel & axle, and screw. Shows how these machines make work easier by changing force, direction, or distance. Machines in action and computer graphics illustrate the principles of work, effort, force, distance, power, friction, and much more. Teacher's Guide available in disk and online: www.schoolvideos.com