The big idea: A design specification turns research findings into criteria a solution can be judged against.
Every line comes from a finding, states what the solution must do, says how it would be tested, and is banded essential or desirable.
One line built from a finding to a testable criterion, three times over, then the essential-desirable split.
Interactive diagram
Explore the labelled diagram, charts and maps for this topic in full study mode.
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it with your first topic free to keep:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Essential
- The solution fails without it
- Safety, the core task, anything a regulation demands
- Used as a filter — an idea that misses one is out
- "Stable with 5 kg placed 50 mm from the working edge"
Desirable
- A real improvement you take if it costs nothing else
- Comfort, appearance, convenience, extra capability
- Used as a tie-break between ideas that all pass
- "Height adjustable without tools"
Marking everything essential destroys the tool: If twelve criteria are all essential, nothing can be traded against anything, and the first real conflict stops the project.
The split exists so that a trade-off can be made honestly and in advance, rather than quietly, late, in favour of whatever is easiest.
| Finding | Criterion | How you would test it | Band |
|---|---|---|---|
| Tips at 4 kg 80 mm from the edge; 9 of 12 twisted to reach | Stable with 5 kg placed 50 mm from the working edge | Load a model at that point and check it does not lift a wheel | Essential |
| Nurses reposition it several times a shift, hands full | Movable and parked with one hand in under 5 seconds | Time 10 nurses moving it clear of a bed and back | Essential |
| Cleaners lose time working round the base | Base clearable in one movement with a floor mop | Ask 6 cleaners to clean a bay and time it | Desirable |
Practice with exam-style questions
Answer exam-style questions and get AI feedback that shows you exactly what examiners want to see in a full-marks response.
Turning a wish into a criterion
Start from the finding, not from the product
Every line should be traceable to something you observed, counted or were told. A criterion with no source behind it is a preference.
Say what it must DO
"Stable when loaded at the working edge" describes behaviour. "Made from steel" describes a solution and rules out better ones.
Attach a number or a condition
5 kg at 50 mm. Under 5 seconds. After 200 wipes. Without a number, nobody can agree afterwards whether it was met.
Write the test at the same time
If you cannot say how you would check it, it is a wish. Writing the test now also means the evaluation at the end is already planned.
The specification is used three more times: To judge ideas against each other, to decide when development is finished, and to structure the final evaluation.
That is why a vague specification costs marks three stages later, long after it was written.
The headings of a specification
Function and performance
What it must do and how well: loads, speeds, run time, accuracy.
User requirements
Ergonomics, ease of use and the needs found in research with the target users.
Materials requirements
Properties the material must have, and any limits set by the process: a 3D printer only prints certain polymers and metals.
Manufacturing requirements
The production method and scale: printing layer by layer limits size, overhangs and finish.
Price and market
Target retail price and cost limits. Price is a constraint on the design, not a statement of how it is made.
Aesthetics, size, safety, environment
Look and feel, dimensions, standards to meet, and end-of-life or material-use limits.
How this is tested — constructing testable specification criteria and banding them. It comes up two ways:
Paper 1 — multiple choice
- Identify whether a stated criterion is testable.
- Classify a criterion as essential or desirable.
Paper 2 — analysing a product
- Construct specification criteria for a named product from given findings.
- Explain why criteria are split into essential and desirable.
The trap: Writing the material or the shape into the criterion. "Made from aluminium" is a solution; the criterion is the behaviour you wanted aluminium for.
From the ward findings — the table tips at 4 kg placed 80 mm from the edge, nurses reposition it several times a shift with their hands full, and cleaners lose time working round the base — construct three specification criteria and band each one.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.