Up, down, or open-moving machines

by Michele Spirn

2006 20 pages eng

History

Simple machines Machines Machine design Lectures et morceaux choisis (Enseignement primaire) Conception et construction Readers (Elementary) Readers (Primary) Anglais (Langue) Ouvrages pour la jeunesse Juvenile literature History

Discusses how simple machines work using drawbridges, escalators, and retractable roofs as examples.

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