Screws All Around

For thousands of years, six simple machines have helped people do amazing things. Each title in this informative series introduces young readers to one simple machine, describing how it works, how it helps people do jobs, and how it is used for fun. For thousands of years, six simple machines have helped people do amazing things. Each title in this informative series introduces young readers to one simple machine, describing how it works, how it helps people do jobs, and how it is used for fun. AGES: 6 to 8