Lessons
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Opening

GROW · SCIENCE · Lesson 2 of 11

You are the circuit fault team

Learning intention

Use a checked low-voltage circuit to compare electrical conductors and insulators.

A lamp is dark. Is the sample the problem?

Your job: check the evidence before classifying it.

Use a paper investigation or supervised low-voltage kit.

Success looks like

  • Describe a complete conducting loop through the cell, lamp and sample.
  • Use a known-conductor check before interpreting an unlit lamp.
  • Choose conductor and insulation materials for a lead, using test evidence.
Retrieval

GROW · SCIENCE · Lesson 2 of 11

Find the missing idea

R1. Name a cell, lamp and wire.

R2. Does one wire from a cell to a lamp make a complete loop?

R3. Are thermal and electrical conductivity the same test?

I do

GROW · SCIENCE · Lesson 2 of 11

Trace the whole loop

The sample bridges a gap in the circuit.

The lamp stays in the loop.

A good connection is needed at every join.

A complete test loopA simple series test circuit with one 1.5 V cell, a matching lamp, closed switch and sample bridging the gap. The lamp remains in the loop so the sample never directly joins the cell terminals.Every part must make a conducting connection1.5 V cellin holderTest sampleMatchinglampSwitch closed for testCrocodile clips touch the sample
A complete test loop
Diagram description

A simple series test circuit with one 1.5 V cell, a matching lamp, closed switch and sample bridging the gap. The lamp remains in the loop so the sample never directly joins the cell terminals.

I do

GROW · SCIENCE · Lesson 2 of 11

One lead needs two properties

Copper provides a conducting path.

Plastic insulates the outside.

Both material choices serve a different purpose.

Different jobs in one cableSimplified cutaway of a low-voltage lead: copper inner conductor provides a current path; plastic outer insulation reduces unwanted contact. This is a diagram, not an instruction to strip a cable.Choose a material for its jobPlastic outer layer: electrical insulationCopper inner path: electrical conductorCutaway model: sizes are enlarged.Do not cut or open real electrical cables.
Different jobs in one cable
Diagram description

Simplified cutaway of a low-voltage lead: copper inner conductor provides a current path; plastic outer insulation reduces unwanted contact. This is a diagram, not an instruction to strip a cable.

Continue within this stage’s shared time.

I do

GROW · SCIENCE · Lesson 2 of 11

Do not trust a single dark lamp

Check copper before the sample.

Check the sample contact, then observe.

Check copper again afterwards.

A no-glow result needs a checkTwo views of a coated metal sample. Clips touching the coating have no reliable connection to the metal core; clips touching prepared exposed ends can make contact. Only the teacher uses a ready-prepared safe sample.Are the clips touching the material we mean?Clips touch coating.Metal core is not connected.Result: uncertain for the metal.Clips touch exposed metal.Check with a known conductor.Then interpret the lamp.Use prepared samples only. No scraping or cutting.
A no-glow result needs a check
Diagram description

Two views of a coated metal sample. Clips touching the coating have no reliable connection to the metal core; clips touching prepared exposed ends can make contact. Only the teacher uses a ready-prepared safe sample.

Continue within this stage’s shared time.

We do

GROW · SCIENCE · Lesson 2 of 11

Fault clinic: sort the case cards

Use the five cases on page 1.

Sort: conductor evidence / insulator evidence / uncertain.

Give the exact clue that supports your decision.

We do

GROW · SCIENCE · Lesson 2 of 11

Repair the reasoning, not the sample

C: foil dark; copper control also dark.

D: coated metal dark; clips touch the coating.

What should we do before making a claim?

Continue within this stage’s shared time.

We do

GROW · SCIENCE · Lesson 2 of 11

Build the class evidence table

Constructed observations from a checked 1.5 V circuit.

Known copper lights before and after this sequence.

Use “in this test” when classifying dark results.

Constructed sample observations; copper controls passed before and after.
SampleLamp observationContact check
Bare copperLightsValid
Bare aluminiumLightsValid
Dry cardNo visible glowValid
Rigid plasticNo visible glowValid

Continue within this stage’s shared time.

Hinge

GROW · SCIENCE · Lesson 2 of 11

The control fails. What now?

A plastic sample gives no glow. The copper control also gives no glow.

You do

GROW · SCIENCE · Lesson 2 of 11

Make your diagnostic report

Choose one response route with page 1 beside it.

Interpret the evidence, then design a two-layer lead.

State one result that must remain uncertain.

You do

GROW · SCIENCE · Lesson 2 of 11

If using the optional kit

Copper check → sample → record → copper check.

Switch off for changes; keep the lamp in series.

Unexpected result? Mark uncertain and ask the teacher.

Continue within this stage’s shared time.

You do

GROW · SCIENCE · Lesson 2 of 11

Use a scientific conclusion

“The lamp lit, which supports …”

“No glow with valid controls supports … in this test.”

“The control failed, so I cannot yet …”

Continue within this stage’s shared time.

Review

GROW · SCIENCE · Lesson 2 of 11

Compare diagnoses

Which uncertain case changed your mind?

Explain why a good scientist may pause a conclusion.

Match conductor and insulation to their jobs.

Review

GROW · SCIENCE · Lesson 2 of 11

Use our voice to improve the test

Choose the class’s most useful next improvement.

Options: clearer contacts, repeated checks, clearer recording.

Explain how your choice improves the evidence.

Continue within this stage’s shared time.

Exit

GROW · SCIENCE · Lesson 2 of 11

Exit diagnosis

E1. Why must the circuit be a complete loop?

E2. Why check copper before and after a sample?

E3. Choose inside and outside materials for a lead.

My science task sheets

Choose one route with your teacher. Shared evidence and the exit sheet appear in every route. Your work stays here while the page is open; save it before closing.

1 • Shared evidence: circuit fault clinic

All observations on this page are constructed sample observations from a 1.5 V cell and matching lamp. No real appliance is tested.

Case A • Copper

Bare copper lights the lamp. Copper control works before and after. Clips have sound contact.

Case B • Dry plastic

No visible glow. Copper control lights before and after. Clips touch the dry plastic correctly.

Case C • Foil

No visible glow. The copper control also gives no glow after the test.

Case D • Coated metal

No visible glow. Copper controls work, but both clips touch paint rather than the metal core.

Case E • Aluminium

Bare aluminium lights the lamp. Copper controls work before and after; contact is sound.

Additional constructed observations for the response routes: dry card has no visible glow with valid contacts and passing copper checks. Copper and bare aluminium light; rigid dry plastic does not visibly light. These observations do not measure exact conductivity.

2 • Supported route: build a sound claim

Use page 1. Point, draw or dictate if useful. Use the same scientific goal.

CaseLights / no glowConductor / insulator evidence / uncertain
A: copper
B: plastic
C: foil

3 • Standard route: a diagnostic report

Use all cases on page 1. A sound report separates valid evidence from an uncertain result.

Sample/caseObserved lampClassificationReason
Copper / A
Plastic / B
Foil / C
Coated metal / D
Aluminium / E

3 continued • Standard route: the material decision

Continue the same route. Use the common evidence page.

4 • Stretch route: when the indicator misses a current

Use page 1. This is supplied evidence, not an instruction to change the classroom circuit.

Constructed evidence from a separate, teacher-controlled measuring circuit: a sensitive current meter detects a small current through graphite. The same lamp gives no visible glow. Checks before and after work. Graphite is a form of carbon and is not a metal.

4 continued • Stretch route: a stronger test

Continue the same route. Use the common evidence page.

5 • Exit and investigation record

Record your own reasoning. If you performed a practical, label observations as your results; otherwise write paper evidence route.

Optional actual test / paper routePredictionObservationControl passed?
Sample 1:
Sample 2:
Sample 3:
Slide 1

TA Brief

Current stage

Objective

Use a checked low-voltage circuit to compare electrical conductors and insulators.

Preparation

Method precautions

Practical alternative

The complete paper fault-clinic uses supplied constructed observations and circuit diagrams. It assesses interpretation and design without handling electrical equipment.

Access and regulation

Supported: Use page 2: trace the loop, classify three provided observations and complete one cable sentence. Read or scribe as required.

Standard: Use page 3: interpret the whole result table, diagnose a failed control and justify both cable layers.

Stretch: Use the Stretch route: evaluate lamp sensitivity and a graphite counterexample, then qualify the electrical-property claim. Same objective, more demanding evidence.

Regulation: Pairs may choose checker, recorder or observer roles. Provide a seated paper route and quiet independent response. Never require touching or handling for participation; no timed wiring contest.

Teacher answers

R1–R3

R1 cell provides the electrical supply, lamp is the light-emitting component, wires make connections. R2 no: there must be a complete loop through both cell terminals and the lamp. R3 no: thermal and electrical conductivity are distinct properties, investigated differently.

W1 / cases A–E

A and E give conductor evidence: bare copper/aluminium light the lamp with controls and contacts valid. B supports classification as a poor conductor/insulator under this low-voltage test: dry plastic gives no visible glow with passing controls. C is uncertain because the known-conductor control fails. D is uncertain for the metal core because clips touch coating; the test concerns the contacted surface.

W2

C: teacher disconnects, checks cell, lamp, leads and switch, restores passing copper check, then repeats the sample and control. D: teacher supplies a safe prepared sample with sound contact to exposed intended material, or records uncertain. Do not scrape/cut samples, add cells or bypass the lamp.

We do table

Copper and bare aluminium provide conductor evidence; dry card and rigid plastic are poor conductors/insulators in this tested setup. No visible glow does not demonstrate zero current or electrical safety at other voltages. These observations are not a quantitative ranking of metals.

Hinge A–D

A wrong: the failed copper check means the plastic cannot yet be blamed. B correct: check circuit and repeat with passing controls. C wrong: investigate equipment/contact rather than claiming copper became an insulator. D wrong: do not add cells; keep the stated safe kit and refer to teacher.

S1–S2

S1 cell, lamp and sample joined in a loop through both cell terminals; an air gap interrupts it and prevents a visible lamp current in this kit. S2 A lights/conductor; B no glow/insulator evidence in this test; C no glow/uncertain because control failed.

S3–S5

S3 copper control; circuit. S4 copper inner path because charge can move readily; plastic outer cover because it resists charge movement and reduces unwanted contact. S5 only that this lamp did not visibly light; very small current may be below the lamp indication threshold.

N1

Copper A: lit, conductor, valid controls. Plastic B: no visible glow, insulator evidence in this test, valid controls and contacts. Foil C: no visible glow, uncertain, failed control. Coated metal D: no glow, uncertain for metal, clips touch paint. Aluminium E: lit, conductor, valid controls.

N2–N3

N2 with switch off use known copper and then switch on to confirm kit works; switch off, connect the prepared dry sample with sound contact and observe; switch off and restore copper, then verify the control still works. Accept equivalent sequence including no bypass of lamp. N3 diagram labels conducting inner copper/aluminium and insulating outer plastic; explain current path and reduced unwanted contact. No real cable dismantling.

N4–N5

N4 low-voltage no-glow results do not establish no current under all conditions. Higher voltages and different conditions can be hazardous; never test mains equipment or bodies. N5 no: visible lamp observations are qualitative, not a measured conductivity ratio. Quantitative comparison needs suitable measurements and controlled sample dimensions and conditions.

T1–T2

T1 reject only metals: graphite is a non-metal and the meter detects a current. T2 the small current may be below that needed for visible lamp glow. A dark lamp reports no visible light in this circuit, not mathematically zero current. Do not increase class voltage to seek a response.

T3–T4

T3 same cell, lamp, leads, sample length/contact spacing and safe contact quality; change sample, check known copper before and after, switch off for changes, record observations and repeat. Limitation: lamp threshold and sample geometry mean qualitative evidence, not exact intrinsic conductivity. T4 C has failed equipment/control validity; D lacks valid contact with the intended metal core.

T5

Conducting inner copper or aluminium enables the current path; insulating outer material helps isolate it. These class observations cannot certify a product for mains wiring, durability or all voltages, nor prove zero leakage current.

E1–E4 / optional record

E1 a connected conducting path is needed around this circuit for a lamp current. E2 establishes the kit worked immediately before and after sample testing; failures require rechecking. E3 copper/aluminium conducting interior; suitable plastic insulating exterior, with functions. E4 relevant improvements: check contacts, repeat with controls, separate observation and inference. Optional actual-test record has no fixed observations: assess truthful recording and sound inference, including uncertain when controls fail. Reflection accepts any evidence-linked revision.

Assessment / re-teach

Secure objective: can trace complete loop, interprets a dark result only after passing controls and valid contacts, and justifies conductor/insulator functions. A material sort without controls is incomplete. Re-teach with Case C beside A: same known copper, different lamp response. Ask what changed about the evidence before retesting conceptual understanding.

Sources checked for this lesson

Word help

electrical conductor
A material through which electric charge can move readily.
electrical insulator
A material through which electric charge moves much less readily.
current
The rate of flow of electric charge.
complete circuit
A connected loop through which a current can flow.
control check
A known test used to check that the method or equipment works.

Cold Call

Give thinking time. Invite a response by voice, pointing or showing work. A pupil can pass; check in privately when useful.

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