Physical forces make things start moving, change direction, speed up, slow down, and stop moving. A force is a push or a pull. A push moves something away from you; a pull brings the thing toward you. A rolling toy works when a pushing or pulling force makes the toy's wheels turn. Rolling toys have wheels and axles. The straight axles hold the round wheels in place. Examples of rolling toys are roller skates, bicycles, wagons, skate boards, and toy cars. A pushing force gets the motion started. The force of friction or an impact causes the toy to stop. Detailed directions are provided for constructing a balloon-powered racer. A suggested experiment guides the reader through steps in comparing the force of friction on a variety of surfaces. Colorful photographs, diagrams and charts aid in understanding the concepts. Includes a table of contents, a glossary, and an index. A good introduction to physical forces for young children. Part of the "Toys and Forces" series. Reviewer: Phyllis Kennemer, Ph.D.