Key Idea: A3.1 taught what the properties ARE. B3.1 is the choosing. Start at the requirement, turn it into a property with a number, and use the essentials as a filter. Texture, form and colour are functional decisions, delivered by a finishing technique. Cost, availability and sustainability then decide between the survivors — and a justified choice cites evidence and names a trade-off.
Paper 1 — multiple choice
- Match a requirement to a property family
- Pick the property that a described failure points to
- Classify a constraint as cost, availability or sustainability
- Identify whether stated evidence is primary or secondary
Paper 2 — analysing a product
- Identify materials for the parts of a named product
- Justify aesthetic choices and the finishes that deliver them
- Evaluate candidates on cost, availability and sustainability
- Justify a material choice with primary and secondary research
Carried into the design project
- Criterion D — the material choice must be justified, not stated
- Criterion E — the environmental cost of what you chose
- Every material line in a specification needs a number and a source
Requirement, property, evidence, trade-off. Four links, and the marks are spread across all four — students who write only the first and the last lose half of them.
| Link | What it must contain | What a weak answer says |
|---|---|---|
| Requirement | Taken from the specification, with a number and a context | "It needs to be strong." |
| Property | The named property, in the right family, that delivers it | "Steel is strong." |
| Evidence | A cited source, or your own test with samples and conditions | Nothing at all — the commonest omission |
| Trade-off | What you accepted in exchange, and why it was worth it | A list of advantages, which reads as a sales pitch |
An essential property is a filter, and cost never buys it back. Coated mild steel in a wet lab is not rejected for being cheap. It is rejected because corrosion spreads under a chipped coating, and no saving fixes that.
Requirement → property → evidence → trade-off, worked three times on one product.
🔒 Interactive diagram
Explore the labelled diagram, charts and maps for this topic in study mode.
| Factor | What students write | What actually decides a choice |
|---|---|---|
| Cost | "Aluminium is more expensive than steel." | Cost per PART, plus processing and waste, over the whole LIFE |
| Availability | "It is available from a supplier." | The right section and grade, lead time, minimum order, a second source |
| Sustainability | "It has a recycling symbol." | Extraction energy, transport, how LONG it lasts, what really happens at the end |
Important: A material name with no property behind it. It is worth nothing on its own. Strength swapped for stiffness. A seat that flexes alarmingly and never breaks still fails. Sustainability answered with a recycling symbol. A long product life is usually the bigger lever.
The three factors rarely agree. Naming the conflict and choosing is the answer.
🔒 Interactive diagram
Explore the labelled diagram, charts and maps for this topic in study mode.
A community centre is replacing the outdoor benches in its courtyard. Justify a material for the seat slats, using primary and secondary research.
🔒 Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Evaluate powder-coated mild steel, anodised aluminium and recycled plastic lumber for the frame and slats of those outdoor benches, using cost, availability and sustainability.
🔒 Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Where does material selection start?
Why will a stronger material not fix a flexing seat?
Why anodise rather than paint?
What does cost actually mean here?
Why is product life part of sustainability?
Why corroborate a supplier data sheet?
Exam tips
- Requirement → property → evidence → trade-off, every time.
- A material name on its own is worth nothing.
- Essentials filter. Cost never buys back a failed property.
- Aesthetic choices need a functional reason and a finishing technique.
- Cost means per part, over the life. Sustainability includes how long it lasts.
- Cite both primary and secondary evidence, and name what you gave up.