How do you choose the best material for a product by matching properties to requirements?
Select an appropriate material for a product by matching its properties to the requirements of the specification, considering cost and availability
A practical answer to the N(A)-Level D&T outcome on material selection. How to match a material's properties to the specification, weigh cost, availability and environment, and justify the final choice.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
SEAB wants you to choose the best material for a product by matching its properties to the requirements in your specification, while also weighing cost, availability and the environment. The skill examiners reward is a justified choice: not just naming a material, but explaining why each property suits the job.
The answer
Start from the specification
The right material is the one whose properties meet your specification. So begin by listing what the product needs: must it be strong, light, waterproof, heat resistant, cheap, attractive? Each requirement points to a property, and each property points to a material.
Match properties to requirements
Work through the requirements one by one:
- Needs to be light to carry: a plastic or aluminium, not steel.
- Needs to survive outdoors: a waterproof plastic, a durable hardwood, or a corrosion-resistant metal.
- Needs to resist heat: a thermosetting plastic or a metal, not a thermoplastic.
- Needs to carry a heavy load: a strong metal or solid hardwood.
- Needs to be brightly coloured without paint: a self-coloured plastic.
A material often has to meet several requirements at once, so look for one that ticks the most boxes.
Weigh cost and availability
Properties are not the only thing. A material must:
- fit the budget, so a cheaper material that still meets the specification may win;
- be available in the size and form you need, and in time.
The perfect material is useless if it is too expensive or cannot be obtained. The best choice balances suitable properties with affordable cost and reliable supply.
Consider the environment
Where the specification or task allows, think about the impact: can the material be recycled, does it come from a renewable source, will it last so it is not soon thrown away? This links material choice to sustainability.
Justify the final choice
State the chosen material and give a reason for each main requirement it meets, then note that it fits the cost and is available. A clear justification is what earns the marks, not the name alone.
Examples in context
Example 1. A garden planter. It must resist water, hold soil and look good outdoors on a budget. A self-coloured waterproof plastic is chosen because it will not rot, needs no paint, and is cheaper than a durable hardwood, meeting the requirements within cost.
Example 2. A workshop bench top. It must take heavy loads and resist dents, so a solid hardwood or thick manufactured board is chosen over plastic, because strength and hardness outweigh the higher cost for this job.
Try this
Q1. State two factors besides properties that affect material choice. [2 marks]
- Cue. Cost (the budget) and availability (whether it can be obtained in the right form and time).
Q2. A product must be light and waterproof for outdoor use. Suggest a material and one reason. [2 marks]
- Cue. A plastic, because it is light and waterproof and will not rot outdoors.
Q3. Explain why the best material is not always the one with the ideal properties. [3 marks]
- Cue. Because an ideal material may be too expensive or unavailable, so the best choice balances suitable properties with an affordable price and reliable supply.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original6 marksA student is choosing a material for a child's outdoor toy that must be light, waterproof, brightly coloured and safe. Recommend a suitable material, and explain how it meets each of these four requirements.Show worked answer →
A suitable material is a thermoplastic such as polythene (or another moulded plastic).
Light: plastics are much lighter than metal or wood, so a child can carry the toy.
Waterproof: plastic does not rot or rust, so it survives being left outdoors.
Brightly coloured: plastic is self-coloured, with colour right through, so it stays bright without paint that could chip.
Safe: plastic can be moulded with smooth rounded edges and no splinters, which is safe for a child.
What markers reward: a sensible material choice, with each of the four requirements clearly linked to a property of that material (light, waterproof, self-coloured, smooth and safe). A choice with no reasons scores little.
Original4 marksExplain why cost and availability matter when choosing a material, not just its properties.Show worked answer →
Even if a material has perfect properties, it is no use if it costs more than the budget or cannot be obtained in time. A cheaper material that still meets the specification is often the better choice, and a material that is easy to get locally avoids delays. So the best choice balances suitable properties with an affordable price and reliable supply.
What markers reward: the points that a material must fit the budget and be available, and that the best choice balances properties with cost and supply rather than picking the ideal material regardless of practicality.
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