From sophisticated computers to a simple pair of scissors - we are surrounded by machines. This lively and practical book looks at the enormous variety of machines and how they work. Fascinating and easy-to-do projects, such as making your own gears and belt drives, constructing a water-wheel and an Archimedes screw, or making your very own vacuum cleaner, will help you to understand the principles that are used to make machines work. Learn About is a series for young readers who want to explore the exciting world of science. Each book covers a different topic, bringing the subject to life with vibrant photographs, drawings and diagrams, which make it fun to learn scientific principles. There are also hands-on projects using everyday objects and equipment, so that young scientists can enjoy finding out the fantastic facts for themselves.