Electricity travels round a circuit, doing work as it goes. It may light bulbs, spin motors, ring bells or buzz buzzers.

The more the electricity has to do, the weaker each of these is likely to be. So, one bulb will light brightly; but two will not be so bright, three will be dimmer, and so on. The electricity is shared between the bulbs - so you don't get two bright bulbs and one dim one, as long as they are all the same type of bulb. The electricity flows round the circuit through conductors. These are materials - like metals - that let electricity through them easily. Electricity flows poorly, or not at all, through insulators. You can draw a circuit to record it. To keep things simple, there are symbols you can use for this.