Readers likely use the wheel and axle machine every day in the form of doorknobs and faucet handles, but this fascinating invention is often overlooked. This book helps readers understand how the wheel and axle simple machine is all around them and helps build compound machines. Approachable text provides lasting knowledge about the forces that make these devices work. Bright full-color photographs including a picture gallery showing familiar objects using this simple machine aid readers in comprehending just how these mechanisms make tasks easier. The concepts in this book enhance a variety of elementary STEM curricula.