The scientific concepts of fast and slow are explained in this book which is one of a series intended to encourage children to explore the science of the world around them. The concepts are explained simply and are supported by activities on every page. Activities are suggested using a variety of simple devices to establish the speed of objects such as: the speed with which a marble rolls down a slope; a homemade speedometer; a pulse check; a test to demonstrate the function of brakes, a home-made parachute; the use of an umbrella to impede speed; a method to measure a child's growth and the use of a stopwatch. Through these practical activities it is hoped children will understand how rockets get into space, what makes machines move fast, how a parachute works, and which animal is the slowest in the world. There are also "did you know" boxes on every page.