Recall the complete circuit from Lesson 10. Today's question: "Which materials let electricity flow, and which block it?" Introduce conductors (let electricity pass) and insulators (block it).
Model the test rig: a simple circuit with a gap, and a globe as the indicator. If the globe lights when a material bridges the gap, electricity flowed through it — it's a conductor. If the globe stays dark, it's an insulator. Think aloud: "The globe is doing the talking. Bright globe = conductor. No light = insulator."
Demonstrate one obvious conductor (a metal spoon) and one insulator (a plastic ruler), then show that a strip of aluminium foil can replace the wire entirely — foil conducts.
Finally, introduce two ways to arrange more than one globe, reading this comparison together:
Note the practical difference: in series, breaking the loop (or removing one globe) stops them all; in parallel, each branch works on its own.
Hand each pair a test kit with a globe indicator and a set of materials (metal, plastic, wood, foil, rubber). As a class, test the first material together and record it, agreeing on the rule: globe lights → conductor; globe dark → insulator.
Pairs test the remaining materials, keeping the test fair (same circuit, same contact each time). Then demonstrate the foil-as-wire idea as a class: replace a wire with a foil ribbon and confirm the globe still lights — setting up the Lesson 12 investigation.
Briefly build series and parallel arrangements with two globes and ask the class to observe what happens to each when one globe is removed.
Pairs complete the conductor/insulator recording table:
- test each material and record whether the globe lit;
- sort each material into conductor or insulator;
- write a sentence explaining how the globe told them the result;
- describe, in one sentence each, the difference between a series and a parallel circuit.
Circulate to check the test stays fair (same circuit each time) and that "dark globe" results aren't caused by a broken connection.
Exit ticket: name one conductor, one insulator, and one place at home where each is useful (e.g. copper wire vs plastic coating).