An introduction to a simple electrical circuit. The battery pushes the electricity along the wires from the positive terminal, through the bulb and back to the negative terminal. This creates a circuit. To turn out the light the circuit needs to be broken by adding a switch. It does not matter where the switch goes as the effect is the same. The bulb glows because electricity flows through the filament. When the bulb gets old the filament breaks and this breaks the circuit.
Could be used as an introduction to an electricity topic in Science or DT. The teacher could ask the children to make the circuit from the clip and break it using a switch. The children could then be given even more batteries, bulbs and wires to see if they can experiment with the additional equipment. The teacher could also ask the children to enlarge the bulb and label it with what happens when the bulb blows.