Presents information on simple machines with a focus on wheels and axles. Explains what wheels and axles are, how wheels and axles work, and includes examples of past and present uses.

Includes index.

What is a wheel? -- Wheels in time -- What is an axle? -- Rolling forward -- Modern wheels -- A wheel with teeth -- The future of wheels -- Gaining an advantage -- Surfing simple machines -- Science in action -- What have you learned?.