Glover, David

Explains the science of how simple machines work, discussing real-life examples, and including activities that illustrate the principles covered.

Uses photographs, illustrations, and simple text to introduce readers to mysteries of outer space, and includes activities and quiz questions.

Discusses various machines and how they work. Includes experiments.

Describes tractor parts, engines, jobs, fun, and safety; shows what these machines looked like when they were first invented; and features quiz questions.