Simple circuits for kids: battery, switch and bulb
Electricity only flows round a closed loop. Once a child sees the loop, switches, broken wires and dead bulbs all make sense.
The idea
A circuit is a loop. The battery pushes, the wires are the road, the bulb is where the push does some work and lights up, and a switch is a gap in the road that you can open or close. If the loop is broken anywhere, nothing flows anywhere, not even up to the gap. Close it, and the whole loop is on at once.
Where kids get stuck
- Thinking one wire from the battery to the bulb is enough. It isn't: there has to be a way back.
- Thinking electricity gets "used up" at the bulb, so the wire after it is empty. The same current flows all the way round.
- Thinking a switch stops electricity only on one side of it. It stops the whole loop.
Try it at home
A 3 V coin cell and an LED (the long leg goes to the + side). Touch both legs to the battery: it lights. Touch one leg: nothing. Hold a bent paperclip between the LED and the battery and lift it: that's a switch. Add a second LED and see what sharing the loop does to the brightness.