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Science and Technology K–6 · Year 6

Conductor or insulator? Testing materials in a circuit

Science understanding: Physical sciences

PracticalLow risk

The idea

Electrical energy is transferred round a circuit only along a complete path of conducting material, so a material placed in a gap in a cell-and-globe circuit sorts itself as a conductor (the globe lights) or an insulator (it stays dark).

What you need

  • 2 AA 1.5 V cells in a holder (3.0 V)
  • 1 torch globe rated 2.5 V 0.3 A in a holder
  • 1 red LED in series with a 100 ohm resistor, as a more sensitive indicator
  • 3 insulated leads with alligator clips
  • test items: steel paper clip, strip of aluminium foil, 10 cm of bare copper wire, a 10c coin, a $1 coin, a pencil sharpened at both ends, plastic ruler, rubber band, wooden pop stick, glass marble, strip of paper, dry cotton string
  • a cup of tap water and a cup of strong salt water (2 tablespoons of salt in 200 mL), each with two bare copper wires held 1 cm apart

How to do it

  1. Build the circuit: cells, globe and two leads with a gap between the free clips. Touch the clips together briefly to check the globe lights, then separate them.
  2. Clip each test item into the gap in turn. Record: lights brightly, lights dimly, or stays dark.
  3. For every item that keeps the globe dark, swap the globe for the LED and resistor (long leg toward the positive end) and test again.
  4. Dip the two copper wires into the tap water, then the salt water, with the globe and then the LED in the circuit.
  5. Sort the items into conductors and insulators in a table, noting any that conduct only a little.
  6. Explain why household wires are copper inside a plastic coating.

What you should see

Every metal lights the globe fully: steel, aluminium, copper, the 10c coin (cupronickel) and the $1 coin (aluminium bronze). The pencil's graphite also lights it, usually less brightly. Plastic, rubber, wood, glass, paper and dry string keep the globe dark, and the LED stays dark with them too: they are insulators. Strong salt water lights the LED clearly and may make the globe glow dimly, best seen in a darkened room: bare wires 1 cm apart and dipped a few centimetres into the brine have a resistance of only an ohm or two, but the reactions at the copper wires use up part of the 3 V, so the current stays well below the globe's 0.3 A; tap water passes far less current and leaves the LED dark or barely glowing. The result is two clear groups, with graphite and salt water showing that not every conductor is a metal.

What changes

What you change
material placed in the gap
What you measure
whether and how brightly the globe (or LED) lights
What you keep the same
  • same cells
  • same globe
  • same leads and clips
  • same length of material between the clips where possible

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

  • Only metals conduct (graphite and salt water conduct too).
  • Conductors are the materials a magnet picks up (aluminium and copper conduct but are not attracted).
  • Electricity leaks out of the end of a wire when the circuit has a gap.

Safety card

Low riskLearners carry it out

Hazards

  • cells get hot if their terminals are joined directly (a short circuit)
  • an LED without its resistor can burn out
  • latex allergy (the rubber band test item is natural rubber latex)

Controls

  • never join the clips together for more than a moment
  • 1.5 V cells only; mains power points are never used
  • LED always used with the 100 ohm resistor
  • check allergy records; leave the rubber band out or use a latex-free band if a learner has a latex allergy

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

  • Science and Technology K-6 Syllabus (2017), current, taught until 2026; code read from the syllabus document on 22 September 2026ST3-8PW-STST3-1WS-S
  • Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; Stage 3 content: 'Pose questions, identify variables and safely conduct fair tests to identify materials that act as electrical conductors or insulators', which sits in the focus area whose knowledge outcome is this one; code read from the outcomes page and the content read from the Stage 3 content page on 23 September 2026ST3-SCI-01
  • Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; code read from the outcomes page on 22 September 2026ST3-PQU-01ST3-DAT-01
  • Australian Curriculum v9AC9S6U03AC9S6I02AC9S6I03AC9S6I04

Sources

The pages the author read to write this activity.

  1. www.scootle.edu.au/ec/search?accContentId=AC9S6U03
  2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/outcomes
  3. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  4. primaryconnections.org.au/teaching-sequences/year-6/circuit-breakers/lesson-5-conductors-and-insulators
  5. primaryconnections.org.au/v84-sequences/circuits-and-switches

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