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.