"Presents information on simple machines with a focus on screws. Explains what a screw is, how screws work, and includes examples of past and present uses. Intended for third to fifth grade students"--Provided by publisher.

Includes index.

What is a screw? -- Sharp threads -- Pushing ahead -- Screwy gears -- Nuts and bolts -- Drilling bits -- Early screws -- Gaining an advantage -- Surfing simple machines -- Science in action -- What have you learned?.