Circuits
Materials that allow electrical energy to flow through, such as metals, are called conductors. Materials such as wood, plastic, and other non-metals, that stop or resist the flow of electrical energy are called insulators. Complete circuits must have an electrical device (light bulb), an energy source (battery), and wires (conductors) connected in a way that electrical energy can flow in a complete loop. If there is a break in the circuit, or an insulator is in the connection, the electrical device will not work and we call it an incomplete circuit.