The iterative design process

Designers rarely get it right first time. They try an idea, test it, learn from it and improve it, again and again.

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What is design and technology?

Design and technology is about solving real problems for real people by designing and making products.
A product can be almost anything that is designed and made: a phone stand, a chair, a sandwich, a bag or a toy.
In D&T you design, make and evaluate, using knowledge about materials, mechanisms, electronics and food.

Designing in a loop

In iterative design, you go round a loop many times:
1. Explore the problem and the user's needs.
2. Create ideas and models.
3. Evaluate: test the idea and get feedback.
4. Improve the design, then go round again.
Each time round is called an iteration. Each iteration makes the design better.

Models and prototypes

Designers test ideas quickly with models: card, paper, foam or a computer model (CAD).
A prototype is an early working version used to test how well a design works before it is made for real.
Mistakes found early are cheap to fix. Mistakes found after a product is made in large numbers are very expensive.
The inventor James Dyson says he made 5,127 prototypes before his first bagless vacuum cleaner worked as he wanted.
Worked example

Leo makes a card model of a desk tidy. When his friend tests it, the pens fall over because the holes are too wide. What should Leo do next in an iterative process?

  1. Testing has shown a problem: the holes are too wide.
  2. In iterative design, he uses this feedback to improve the design.
  3. He changes the hole size, makes a new model and tests it again.

Answer: Make the holes narrower, build a new model and test it again with the user.

Key idea

Iterative design is a loop: explore, create, evaluate and improve, then repeat. Models and prototypes let designers test ideas cheaply before making the final product.

Key words
Iterative design
Designing in a repeated loop of exploring, creating, testing and improving.
CAD
Computer-aided design: using software to design products in 2D or 3D.
Prototype
An early working version of a product, used to test a design.

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Extra practice

2 more questions

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  1. Which describes iterative design?

    1. Design once and never change it
    2. Copy an existing product
    3. Design, make, test and improve, then repeat
    4. Test only at the very end
    Show the answer

    Answer: Design, make, test and improve, then repeat

    Each loop improves the design.

  2. A designer makes a model, tests it and improves it three times. How many iterations is this?

    1. 1
    2. 0
    3. 3
    4. 6
    Show the answer

    Answer: 3

    Each loop is one iteration.

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Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.

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