Amazon.com description: Product Description: Focusing on the six simple machines--levers, wheels and axles, pulleys, screws, inclined planes, and wedges--this fun and informative series introduces young readers to several basic concepts of physics--such as work, force, gravity, and friction. Includes easy-to-do experiments, colorful photographs, clear text, and fun activities. Supports the national science education standards Unifying Concepts and Processes: Evidence, Models, and Explanation; Unifying Concepts and Processes: Form and Function; Science as Inquiry; Physical Science; and Science and Technology as outlined by the National Academics of Science and endorsed by the National Science Teachers Association.