What makes it possible for plants to grow? What makes it possible for you to move your arm to raise your hand in class? What makes it possible for your house's lights to turn on? The answer is energy! Energy is the capacity for doing work. This book focuses on the different types of energy, including potential, kinetic, thermal, electrical, chemical, and nuclear. Readers will learn about properties of energy, how energy is measured, and major sources of energy. Primary sources show energy in action. This book will captivate young scientists.