Science plays a big role in how we create and use the tools and machines that help us in our daily lives. Scientific Principles can be found at work in everything from the simplest hammer to the complex robotic devices found in modern factories. Tools and Machines describes how humans first started using tools and traces the evolution of tools from simple stone implements to the high-tech devices of today. Along with full-color photographs and illustrations, this volume features simple experiments that clearly illustrate the science concepts behind tools and machines.Experimenting with Everyday Science investigates the science at work in our daily lives. Each book in the set provides historical background and "how things work" explanations that cover earth science, biology, chemistry, and/or physics topics. To build on these ideas and make scientific concepts clearer, each book also features at least 25 hands-on, illustrated experiments that readers can do using simple materials found at home or school.