Electricity flows as long as a complete circuit is in place. A switch acts like a gate in that circuit. When the switch is turned on, it completes the circuit. The electricity moves across the switch and keeps travelling. When you turn the switch off, it breaks the circuit.

Twist the ends of two pieces of wire around the drawing pins. Push the drawing pins into the cork. Attach one wire to the battery and the other to the bulb holder. Place the tin foil across the drawing pins to test your circuit. If the bulb lights up, it is ready.

Now place one end of the paper clip around one drawing pin. Bend the paper clip so it does not touch the other drawing pin. The paper clip is your switch - press it down and see what happens!