Key Stage 3 design and technology · Design

KS3 design and technology: writing a design specification

A specification is the list of requirements a product must meet. In Key Stage 3 design and technology, pupils learn to develop specifications that inform the design of innovative, functional and appealing products which respond to needs in a variety of situations. A good specification is specific and testable, and it is what the finished product is judged against.

Writing a design specification, explained

After researching users and defining a problem, pupils write a specification. It turns what they have found into a checklist of requirements. Instead of “the product should be strong”, a specification says exactly what that means. The programme of study asks for specifications that lead to products that are innovative (new or better in some way), functional (they work well for their purpose) and appealing (people want to use them), and that respond to needs in a variety of situations, whether in the home, at leisure or in industry.

Specifications usually cover several headings. Function: what must it do? Size and shape: how big can it be, and does it have to fit something? Materials: what is it made from, and why? Aesthetics: how should it look and feel? Safety: what could harm someone? Ergonomics: how well does it suit the human body? Cost and manufacture: what can be afforded, and how can it be made with the equipment available? Sustainability: can materials be reused or recycled, and how long will it last? Schools choose their own headings, and some use a mnemonic to remember them.

The big idea is that each point should be measurable or testable. “Easy to use” is a wish, while “can be assembled by an eleven year old in under five minutes without tools” is something a pupil can test and mark as met or not met. Pupils are taught to link each requirement to their research (“because users said…”), and to separate essentials from extras with labels such as “must”, “should” and “could”. That helps them make trade-offs when time or money is limited.

A specification is also a working document, not a fixed one. Pupils use it to judge their early ideas, to decide between designs, and later to evaluate the prototype and finished product against each point. When testing shows that a requirement is unrealistic, or that a new one is needed, they can reformulate and update it. It is also a place where they can show how they avoided stereotypical responses, by ensuring the requirements reflect the real range of users and not only assumptions.

For parents, the useful thing to know is that this part of a project can look like dull writing, but it is where the quality of the design is decided. A pupil with a precise specification can make confident choices, while a pupil with vague aims often struggles to say if the final product works.

Words your child will hear

Specification: A list of requirements that a product must meet, written so that it can be tested.
Criteria: The standards used to judge whether a design is successful.
Function: What a product does, and how well it does it.
Aesthetics: How a product looks, feels, sounds or smells, and why people find it appealing.
Ergonomics: How well a product fits and suits the people who use it.
Measurable: Written with a number, size or clear test so you can check it.
Trade-off: Giving up some of one quality, such as cost, to improve another, such as strength.

What the National Curriculum says

The programme of study for Key Stage 3 says:

When designing and making, pupils should be taught to develop specifications to inform the design of innovative, functional, appealing products that respond to needs in a variety of situations
When designing and making, pupils should be taught to identify and solve their own design problems and understand how to reformulate problems given to them

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: a specification for a phone stand

Research shows that users want a stand to hold a phone upright at a desk for video calls. Turn the vague wishes “strong, small, nice-looking, safe” into a specification that can be tested.

List the findings from research. Users said the stand should keep the phone steady, fit on a small desk, work with different phone sizes, and look neat. Each finding will become a numbered requirement.
Make each wish measurable. “Strong” becomes “holds a phone weighing up to 250 g without tipping when the screen is tapped”. “Small” becomes “base no bigger than 10 cm by 10 cm”. Check that you can test each one.
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Strong: holds 250 g, no tipping
Small: base 10 cm x 10 cm or less
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Cover the other headings. Adjustable angle between 45 and 75 degrees. Slot wide enough for phones from 6 mm to 12 mm thick. Smooth, rounded edges. Made from recycled or recyclable material where possible.
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Angle: 45 to 75 degrees
Slot: fits 6 mm to 12 mm thick
Edges: no sharp corners
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Label what is essential. Use “must” for safety and function, “should” for appearance and finish, “could” for extras. The tipping test and the safe edges are musts. A choice of colours is only a could.
Say how each will be tested. Place the phone, tap the screen and see if it tips. Measure the base with a ruler. Use a protractor to check the angles. Ask users to rate the look of the stand.

A numbered list such as: must hold 250 g without tipping; must have a base no larger than 10 cm by 10 cm; must have no sharp edges; should fit phones from 6 mm to 12 mm thick; should adjust between 45 and 75 degrees; could come in more than one colour. Each point has a test.

Common mistakes and how to help

Writing vague requirements such as “it must be good quality”

Words like “strong”, “nice” and “easy” feel complete, so pupils don’t see that nobody could mark them as met or not met.

What helps: Ask, “How could you test that?” Keep asking until a number, a size or an observable test appears.

Copying a specification from an existing product or the internet

A pre-written list looks professional and saves effort, but it doesn’t match their own users or research.

What helps: Check that every point can be traced back to something they found out. If they cannot say why a requirement is there, it probably should not be.

Treating the specification as finished once written

Pupils think of it as a piece of homework to hand in, not a tool to use.

What helps: Encourage them to refer back to it when choosing between ideas, and to update it if testing shows a problem. Revising it is good practice.

Making everything essential

Pupils want every feature, so every line becomes a must. Real projects have limits on time, money and materials.

What helps: Ask which three requirements matter most and what could be left out if time ran short. This is the same kind of choice professional designers make.

How to help at home

Turn a wish into a test. Pick an object at home and a quality such as “comfortable” or “durable”. Ask your child how you could measure it. A bag might carry 3 kg for ten minutes without the strap slipping.
Write a specification for a family purchase. Before buying something, like a water bottle or a desk lamp, ask your child to list what it must, should and could do. Compare the options against the list afterwards.
Help them measure. Measurements make a specification real. Let your child use a ruler, tape measure or kitchen scales to check the size and weight of what they are designing for.
Look at the trade-offs. When shopping, talk about what you gave up to get something: cheaper but less durable, or lighter but less strong. This is the thinking behind labelling requirements as must, should and could.
Ask them to evaluate against the list. At the end of a project, ask which points in the specification the product met and which it missed. Honest evaluation is a strength, not a weakness.

Builds on

Key Stage 2: Research and design criteria
Key Stage 2: Sketches and exploded diagrams
Key Stage 2: Prototypes, patterns and CAD