ScienceGrade 9ages 14–15
💡 A circuit needs a closed loop
A child wires a battery to a bulb with a single wire, nothing lights, and it looks like a mystery — because the natural assumption is that current just needs to "reach" the bulb, when it actually needs a complete path back to the battery to flow at all.
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Download on the App StoreWhat your child learns
- The charge is already all along the wire. The battery does not supply it, it pushes it.
- A push moves the whole chain at once, the way a bicycle chain starts moving all together.
- A gap means the charge would have to pile up at the end with nowhere to go.
- So a gap anywhere stops the flow in the whole circuit, and not only next to itself.
The mistake most kids make here
Touching the bulb is enough, or one wire with no return lights it.
Try one question
A bulb lights when…
Lights when
- the loop is closed
- there is a gap in the path
- the wire is made of wood
Answer
the loop is closed — Yes. Only when there is a way back can the charge move, and when it moves the bulb heats.
How Maya teaches it
Your child tells Maya what they did in class. She teaches this topic at her desk, asks questions with tappable answers, and when the answer is wrong she explains why that answer was tempting instead of saying “try again”. She remembers what did not land and comes back to it.
Your child has it when they can: Say why a gap in the wire turns a bulb off.
How to help at home
This is one of the most common first mistakes in electricity, and it's a reasonable one: a hose only needs to reach a plant to water it, so a wire "reaching" a bulb feels like it should be enough. Electricity doesn't work that way — it needs somewhere to go, not just somewhere to arrive.
If you have a battery, a bulb, and wires at home (even a simple kit), try connecting only one wire from battery to bulb and ask your child to predict if it lights. It won't. Then close the loop with a second wire back to the battery — now it does. The comparison is the whole lesson.
When your child says "it should light, the wire is touching it," ask: "where does the charge go after the bulb — does it have a way back?" That question redirects from touching to looping, which is the real requirement.
A good sign she has it: given a drawn circuit with a gap anywhere in the loop — even far from the bulb — she can say correctly that the bulb stays dark, because she understands the whole loop has to be closed, not just the part near the bulb.
Questions parents ask
- Why won't my child's bulb light even though the wire is touching it?
- Touching isn't enough — current needs a complete, closed path from one battery terminal, through the bulb, and back to the other terminal. A single wire only gets current to the bulb, with nowhere for it to return, so nothing flows.
- Does it matter where the gap is in a circuit?
- No — a gap anywhere in the loop stops the whole circuit, not just the part near the gap. Current can't build up and "wait"; if there's no complete path, nothing flows anywhere in that loop.
- What's a simple way to explain a closed loop to a 9th grader?
- Compare it to a bicycle chain: pedaling only turns the wheel if the chain forms a complete loop around both gears. Cut the chain anywhere and the whole thing stops moving together, just like a circuit with any gap.
- How does Maya teach this differently from a diagram?
- Maya asks the child to trace the path a charge would take, out from the battery and all the way back, rather than just checking if the bulb is "connected," so the idea of a full loop — not just contact — becomes the test.
No card needed. The first lesson is free.
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Sources: Next Generation Science Standards