4Pe.01: A device only works when the circuit has no gaps (lighting a bulb…

Simple Circuits: Make It Light Up Grade 4

Light a bulb with one wire, hunt for materials that let electricity through, find out why string lights all go dark at once, and build a burglar alarm. Four hands-on lessons on closed loops, safe and cheap.

• Can you light a bulb with one wire? 45–60 min

  Teams get one AA battery, one wire and one small bulb, and keep trying until the bulb lights, drawing every setup that works and every one that doesn't. Then they explain why a bulb only lights when electricity can travel in a complete loop.

• What lets electricity through? 45–60 min

  Teams build a circuit tester with a gap in it, then bridge the gap with coins, foil, pencil graphite, an eraser, paper clips and plastic. They sort the results into conductors and insulators and explain why electrical wires are metal on the inside and plastic on the outside.

• Why do some string lights all go out at once? 45–60 min

  Teams wire two bulbs in a single loop, then in two separate loops, unscrew one bulb each time and compare brightness. They explain why one loose bulb can darken a whole string of lights, and why a house is wired so it doesn't.

• Can you build a burglar alarm? 60–75 min

  Teams design and build a homemade switch from a clothes peg or foil and cardboard that closes a circuit when a door or box lid opens, sounding a buzzer or lighting an LED. They test it, improve it and use evidence to argue their alarm is the most reliable.