Conductors vs Insulators

Stage: Year 7-9 / KS3 (Ages 11-14) Time: 1 hour Subjects: Science (Physics & Materials) Board: SPOKE (full board recommended for LED feedback — SPOKE-mini works too if paired with a computer for audio confirmation)

Learning Objectives

• Understand the difference between electrical conductors and insulators

• Form a hypothesis and test it using a fair, repeatable method

• Use the SPOKE board's capacitive touch sensors to test a range of materials

• Record and interpret experimental results, grouping materials by how reliably they conduct

Overview

Pupils use the SPOKE board as a simple material tester. Each SPOKE pad is a capacitive touch sensor: it detects a conductive object by sensing a small change in the electrical field around the pad, not by completing a circuit. By connecting a crocodile clip to a pad and touching a range of everyday objects, pupils can see directly which materials are conductive enough to register and which are not.

Materials Needed

• SPOKE board

• Crocodile clips and wire

• A range of test objects: metal (coins, cutlery, foil), non-metals (plastic ruler, wood block, rubber, glass), organic/damp materials (fruit, a leaf, a cup of water), paper, and fabric

• A simple prediction/results recording table (printed or drawn)

• Computer with a web browser, for audible confirmation via the SPOKE Play page — optional

Instructions

1. As a class, discuss what "conductor" and "insulator" mean, then introduce capacitive touch sensing: the SPOKE board detects a conductive object by sensing a small change in the electric field around a pad, not by completing a circuit

2. In small groups, gather a set of test objects covering metals, plastics, organics, and fabrics

3. Before testing, predict which materials will trigger a pad and which won't, recording predictions in a table

4. Connect a crocodile clip to a SPOKE sensor pad and touch the free end to each test object in turn

5. Record whether each material triggers the sensor (LED lights up or a sound plays) or not

6. Compare predictions to results as a class and discuss any surprises

7. Group the tested materials into "reliable conductors", "unreliable or partial conductors", and "insulators"

8. As a demonstration, try touching a non-conductive material (like paper) with a layer of foil hidden behind it, and discuss why it still triggers the sensor

Teacher Tips

• Damp or fresh materials (fruit, leaves, skin) generally trigger the sensor more reliably than dry ones

• Some plastics or dry wood may give inconsistent readings — a good opportunity to discuss real-world measurement variability

• Emphasise that touching a pad doesn't "complete a circuit" in the traditional sense — it changes the electric field the board is measuring

• Connecting to the SPOKE Play page (spokeboard.com/play) for audible feedback makes results easier to confirm as a class

Extension Ideas

• Investigate whether material thickness or moisture level changes the results

• Test the "hidden conductor" exception more rigorously — how thick can a non-conductive layer be before it stops registering?

• Link to the Fruit Piano lesson (Year 5-6) or Copper Tape Poster project as a creative follow-on application

A capacitive sensor can also be triggered through a non-conductive material if there's enough conductive material behind it — this is a genuine property of the SPOKE board's sensing, not a fault, and makes for a good class discussion point.