Safe circuits with a battery, a bulb and a wire
Low-voltage hands-on activities that pair with Circuit Rescue, with safety rules and questions to ask.
Circuit Rescue lets you test circuits quickly and without risk. These activities let you confirm the same ideas with real parts. Each takes 10–15 minutes. Try them before or after a few missions.
Safety first
Use only AA or AAA batteries (1.5 V each). Never use wall sockets, mains adaptors, or car batteries. Supervise anyone new to this, and keep button batteries away from young children, since they are dangerous if swallowed.
- Never connect a wire directly from one end of a battery to the other. That is a short circuit. The wire and the battery can get hot very quickly. This is exactly what the game's short-circuit warning shows.
- Disconnect the battery when you are not testing.
- Do not use rechargeable lithium packs, such as phone batteries, for these activities.
What you need
- 2 AA batteries, and battery holders if you can get them
- 2 small torch bulbs (1.5–2.5 V) in bulb holders, or small LEDs with resistors
- Several short wires, with crocodile clips if possible
- A paper clip, a drawing pin and some foil for the switch
- Some everyday objects to test: coin, rubber, pencil, plastic spoon, key, paper
Activity 1: Light the bulb
Ask: Can you make the bulb light with one battery, one bulb and two wires?
Let learners try different arrangements. Many will touch one wire to the battery and one to the bulb and see nothing. That is the point. Ask them to look at where the loop is broken.
Link to the game: Mission 1, First light.
Questions:
- What had to happen for the bulb to light? (A complete loop from one end of the battery, through the bulb, and back to the other end.)
- Does it matter which way round the battery goes? (Not for a bulb. Try it.)
Activity 2: Conductor or insulator?
Break the loop, then try to close the gap with each object. If the bulb lights, the object conducts electricity. If not, it is an insulator.
Make a prediction table first. Metals usually conduct. Plastic, rubber, paper and wood usually do not. Pencil lead (graphite) is a surprise: it conducts, a little.
Questions:
- Why are electrical wires covered in plastic? (To stop electricity going where it should not, and to protect people.)
- Why are the metal parts of a plug made of metal? (They need to conduct.)
Activity 3: Build a switch
Fix a paper clip to a piece of card with a drawing pin so that it can swing, and put a second pin, or a strip of foil, where the clip can touch. Wire it into the loop. The paper clip closes and opens the gap.
Link to the game: Mission 2, Flip the switch.
Activity 4: Chain or side by side?
Use two bulbs and one battery. First wire them in a chain (series), then side by side (parallel). Compare the brightness, and unscrew one bulb each time.
| Series (chain) | Parallel (side by side) | |
|---|---|---|
| Brightness | Dim | Bright |
| Unscrew one bulb | Both go out | The other stays on |
| Battery lasts | Longer | Shorter |
Real torch bulbs behave a little differently from the game's tidy bulbs, so the dimming may be less dramatic with 1.5 V batteries. Dim is still dim.
Link to the game: Missions 3 and 4.
Activity 5: Batteries end to end
Light one bulb with one battery. Then add the second battery end to end. The bulb should get brighter. Try side by side, and try one the wrong way round.
Link to the game: Mission 5, Power boost.
Safety reminder: more batteries means more power, and a small bulb can burn out. Stop at two.
Questions that match each mission
| Mission | Question to ask before play |
|---|---|
| 1. First light | What does the electricity need in order to flow? |
| 2. Flip the switch | What is a switch doing to the loop? |
| 3. One chain | If both bulbs share the battery, will each be brighter or dimmer? |
| 4. Side by side | How can both bulbs get the full push? |
| 5. Power boost | How do you make the pushes add up? |
| 6. Spaceship lights | Where must the switch go to control all three bulbs? |
Common misconceptions
- "Electricity gets used up in the bulb." The current is the same all the way around a simple loop. It's energy that gets transferred to the bulb as light and heat. The water-pipe picture helps: water is not lost when it goes past a bumpy part, but it does give up some of its push.
- "The first bulb in a chain gets all the electricity." They are the same brightness, because the same current flows through both.
- "Batteries store electricity." They store chemical energy, and they push electricity around the loop while they are connected.