People love to play! From zooming down roller coasters to riding bikes, we like to be in motion. In this book, you'll learn about how engineers use science to increase safety and fun for roller coasters, zip lines, helmets, and more. The My Engineering Library series provides an introduction to a variety of engineering and design topics for beginning readers based on the Next Generation Science Standards (NGSS). From learning about how engineers design rockets to how they build structures underwater, these informative books present complicated information in easy-to-understand language with kid-friendly examples and diagrams. Each book includes an activity to support further comprehension.