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
- 21 parts to scroll through
- 4 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 21
Visual introductionPicture this
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.
In a nutshell
Develop, test and evaluate iterative design solutions against a user specification.
Learning cycle
Part 2 of 21
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.
Explore the idea
Part 3 of 21
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.
Reset break
Part 4 of 21
Pause
That's sitting 1 of 5 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.
Explore the idea
Part 5 of 21
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.
Quick check
Part 6 of 21
Quick check
Part 7 of 21
Reset break
Part 8 of 21
Pause
That's sitting 2 of 5 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.
Learning cycle
Part 9 of 21
Learning cycle 2 of 2
Part 2 · Modelling and iteration
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 21
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.
Explore the idea
Part 11 of 21
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.
Reset break
Part 12 of 21
Pause
That's sitting 3 of 5 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.
Quick check
Part 13 of 21
Quick check
Part 14 of 21
Explore the idea
Part 15 of 21
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.
Reset break
Part 16 of 21
Pause
That's sitting 4 of 5 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.
Challenge round
Part 17 of 21
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
Challenge round
Part 18 of 21
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.
Challenge round
Part 19 of 21
Game · Recall cards
What makes a specification point testable?
Card 1 of 4
Mastery quiz
Part 20 of 21
Marked quiz
End of lesson quiz: Iterative design: from context to evaluated prototype
4 questions, marked with the reasoning shown. No timer.
1. What makes a specification point testable?
2. What is anthropometric data?
3. What should each iteration record?
4. Which evaluation approach scores best?
Lesson round-up
Part 21 of 21
Lesson round-up
Ready when you are
Quiz score
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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 LunaPart 1 of 21 · Watch & discover