---
title: "Iterative Design and Prototyping"
description: "Develop a design through repeated cycles: build a model or prototype, test it against criteria, record the results, and use the evidence to choose changes. Retest to find whether a change helps and wh"
canonical: https://lightmysky.com/learn/design-and-technology/iterative-design-and-prototyping-mt_fYD3KaViOZ
source: https://lightmysky.com/learn/design-and-technology/iterative-design-and-prototyping-mt_fYD3KaViOZ.md
retrieved: 2026-11-12
---

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# Iterative Design and Prototyping

Develop a design through repeated cycles: build a model or prototype, test it against criteria, record the results, and use the evidence to choose changes. Retest to find whether a change helps and what still needs work.

Subject: Design & Technology · Area: Designing & Making · Ages 11 to 14
Page: https://lightmysky.com/learn/design-and-technology/iterative-design-and-prototyping-mt_fYD3KaViOZ

## Ready when they can

- Build a rough prototype or model to test an idea before making a final version
- Test a prototype against criteria, record the results, and identify the main weakness (e.g. 'the bridge failed at the joints, not the beams')
- Explain how each version changed and what test evidence prompted the change

## Lesson: The Build-Test-Improve Loop

A prototype is a model made to test a design idea before the final product. It may test just one feature. Use the criteria from your brief: what must the design do, and what limits must it meet? Iterative design means building, testing, learning from results, changing the design and testing again. A change may help, do nothing or create another problem.

*(drawing: Use the test evidence to choose the next change. Repeat when more work is needed.)*

**Example.** Zara's bridge model held 2 kg before its joints separated. Its beams stayed intact. She changed the joint method. With the same test setup, version two held 4 kg. The increase was 4 minus 2, or 2 kg. Changing one feature while keeping test conditions alike helps compare its effect. One result is evidence; repeat tests where practical.

Record the version, what changed, the evidence behind the change and the new test results. Observe where and when a problem happens. Investigate that part first, then choose a change supported by evidence. Several parts may need changing, or a new approach may be needed. Retesting checks whether the proposed fix helped. Finding a weak point alone does not prove the cause.

Choose a prototype that can answer your test question. A sketch can test layout, but testing a bag with books needs a physical model with suitable materials and joins. A cheap material may behave differently from the final one. Check other criteria after a change: a stronger design may cost or weigh more. Use adult-approved tools and safe tests for classroom models.

**Recap.** Build a suitable prototype, test against criteria, record the evidence, choose a change and retest. Check whether it helped and what still needs work.

*Original lesson, questions and flashcards written for this dataset about prototyping, test evidence and design iteration.*

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Design briefs and better products](https://lightmysky.com/learn/design-and-technology/design-briefs-and-better-products-mt_QeNClHE0EG)

## Optional connections

- [Using Tools Safely](https://lightmysky.com/learn/design-and-technology/using-tools-safely-mt_8_IFOc79VA)
- [Fair testing (age 8+)](https://lightmysky.com/learn/science/fair-testing-age-8-mt_eoPcc4nrBE)
- [Strengthening Structures](https://lightmysky.com/learn/design-and-technology/strengthening-structures-mt_QnYDI3itJY)

## Opens up

- [CAD and making by machine](https://lightmysky.com/learn/design-and-technology/cad-and-making-by-machine-mt_jNf8g85YbY)