In this illustrated book, students are introduced to the concepts of energy, electrons and electrical energy. They learn about voltage, current and resistance, and Ohm's law, which relates to all three. Students learn where the energy to light the light bulbs comes from, and how it can be turned on and off. The book includes activities which direct students to connect light bulbs to batteries with wires, and experiment to find out what happens when they use more batteries, or more light bulbs, or different kinds of wire.