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Design & TechnologyGCSE design and technology: designing and iterating30 min★★★ difficulty

Iterative design: from context to evaluated prototype

Iteration is not drawing the same idea three times. It is testing, learning something specific and changing the design because of it.

Lesson overview

What you'll learn in this lesson

Develop, test and evaluate iterative design solutions against a user specification.

Key learning points

  • • Context, client and user
  • • Writing a specification
  • • Modelling and iteration
  • • Evaluating

This lesson at a glance

  • 30 minutes
  • 17 parts to scroll through
  • 4 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

iterativedesignsolutionsspecificationcontext

Scroll down — the lesson carries on below

Part 1 of 17 · Discover6%
1

Watch & discover

Part 1 of 17

Watch first

Iterative design: from context to evaluated prototype

An English teaching video on this topic from Mr Leisk D&T. Watch it, then scroll down for the lesson.

In a nutshell

Develop, test and evaluate iterative design solutions against a user specification.

2

Learning cycle

Part 2 of 17

Learning cycle 1 of 2

Part 1 · Context, client and user

A short piece of teaching, then a check to make sure it has landed.

3

Explore the idea

Part 3 of 17

Learn

Context, client and user

Start from a context, identify a real user and investigate their needs through interview, observation and product analysis. Anthropometric and ergonomic data turn those needs into measurable requirements, which is what makes a specification testable.

4

Explore the idea

Part 4 of 17

Learn

Writing a specification

Each point should be measurable and justified: 'the handle must be between 100 and 120 mm long so it fits the fifth to ninety-fifth percentile hand width' rather than 'the handle must be comfortable'. Cover function, user, materials, manufacture, cost, aesthetics and sustainability.

5

Quick check

Part 5 of 17

Quick check

What makes a specification point testable?

6

Quick check

Part 6 of 17

Quick check

What is anthropometric data?

7

Learning cycle

Part 7 of 17

Learning cycle 2 of 2

Part 2 · Modelling and iteration

A short piece of teaching, then a check to make sure it has landed.

8

Reset break

Part 8 of 17

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
9

Explore the idea

Part 9 of 17

Learn

Modelling and iteration

Card, foam and 3D-printed models test scale, grip and assembly cheaply. Each cycle should record what was tested, what was learned and what changed. Photographs annotated with the change and the reason are worth more than a page of unexplained sketches.

10

Explore the idea

Part 10 of 17

Learn

Evaluating

Test against each specification point, gather user feedback, and state what you would change with reasons. Honest evaluation of a failure, with a proposed fix, scores better than claiming the prototype met everything.

11

Quick check

Part 11 of 17

Quick check

What should each iteration record?

12

Quick check

Part 12 of 17

Quick check

Which evaluation approach scores best?

13

Explore the idea

Part 13 of 17

Worked example

Worked example: one iteration recorded properly

Test: three users held the card model of the handle for ninety seconds. Result: two reported pressure on the index finger where the moulded ridge sat, and one could not hold it steadily with a gloved hand. Change: the ridge was removed and replaced with a shallow 3 mm recess, and the overall grip diameter was increased from 28 mm to 34 mm to suit gloved use. Justification: the specification requires comfortable one-handed use for at least two minutes, and the wider diameter matches published hand-grip data for the ninety-fifth percentile. The next model will be 3D printed so the recess depth can be tested in a rigid material rather than card.

14

Challenge round

Part 14 of 17

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

15

Challenge round

Part 15 of 17

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

Start from a ____, identify a real user and investigate their needs through interview, observation and product analysis.

Anthropometric and ergonomic data turn those needs into measurable requirements, which is what makes a ____ testable.

16

Mastery quiz

Part 16 of 17

Marked quiz

End of lesson quiz: Iterative design: from context to evaluated prototype

4 questions, marked with the reasoning shown. No timer.

  1. 1. What makes a specification point testable?

  2. 2. What is anthropometric data?

  3. 3. What should each iteration record?

  4. 4. Which evaluation approach scores best?

17

Lesson round-up

Part 17 of 17

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Report

Why the first prototype broke

A team designed a phone stand from 3 mm plywood. The brief said it must hold a 200 g phone at 60° and survive being knocked. The first prototype looked right but snapped at the joint after two knocks.

The team tested again and found the grain of the plywood ran across the narrowest part of the joint, so the wood split along it. They widened the joint from 8 mm to 20 mm, turned the piece so the grain ran along the load, and added a small fillet at the corner to spread the force.

The second prototype survived twenty knocks. It used 15% more material and took four minutes longer to cut — a trade-off the team recorded in their evaluation.

Written for Good Learning Co.

Reading questions

  1. Name the fault in the first prototype and explain why it happened.
  2. List the three changes the team made and what each one does.
  3. Write an evaluation of the second prototype against the brief, including the trade-off.

  • Design sheet

    Diagram

    Sketch two ideas with measurements and notes, then photograph the sheet.

    2 labelled sketches

  • Evaluation

    Writing

    Write how well your idea meets the brief and what you would change next time.

    6–8 sentences

Saved as you type.

Part 1 of 17 · Watch & discover

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