Using Simple Machines explains the simple machines that people use every day at home, in sports, in construction, and in health. While each of the four books focuses on a different area where simple machines are used, the same key concepts are developed across books to help students focus on the big ideas. The theme explores how machines help people do work. It also explains and gives examples of the six different simple machines and discusses how simple machines are put together to make compound machines. Students use the specific content and vocabulary within each book to discuss and examine these big ideas, or Key Concepts. The Theme Set Program is designed for differentiated instruction. Each Theme includes four books written at four different reading levels.