№ 13 · you build it
Either one will do
Two switches side by side: either one lights the light.
- 1Tap the battery, then the button — and the battery, then the switch.
- 2Tap the button, then the resistor — and the switch, then the resistor.
- 3Tap the red light, then the battery.
NOW Tap the battery, then the button — and the battery, then the switch.
What to look for: Hold the button and it lights. Let go and flick the switch and it lights again. Each one is its own way round.
Why it works: Each switch is its own road to the light. Electricity only needs one open road, so either switch will do. Closing both does not make it any brighter.