Select materials and components for a purpose
Compare material families, stock forms, properties, uses and environmental effects, including components and electronic symbols.
This lesson is original StudyForA learning support aligned to Cambridge International AS & A Level Design & Technology 9705. It is not Cambridge material or an official mark scheme. Practical activity must follow the learner's centre procedures and trained supervision.
Before you begin
- Read the product brief and identify its intended user and context.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What should support a material choice for a load-bearing part?
What you will learn
- 9705 T8 paper board modelling
- 9705 T8 woods metals
- 9705 T8 polymers composites
- 9705 T8 smart modern biodegradable
- 9705 T8 components properties
Compare families using evidence
Paper and board include copier paper, card, corrugated and moulded forms. Modelling materials include foams, balsa, polymorph and plaster. Woods include local softwood and hardwood examples; metals include ferrous and non-ferrous families. Polymers include thermoplastics, thermosets and elastomers; composites combine materials to produce a useful property balance.
Smart materials respond reversibly to environmental change. Modern materials are engineered for improved properties; biodegradable materials break down through microbial action under suitable conditions. Compare exact grades and stock forms rather than generalising from a category name.
Connect property, component and use
Hardness, ductility, toughness, brittleness, elasticity, malleability, dimensional stability, electrical and thermal conductivity, and corrosion resistance affect a product's performance. Explain the property needed, then choose evidence about the exact material and form.
Components may include electronic parts and control elements. Use the syllabus symbol list to identify them accurately. Check availability, safety, processing, cost and environmental impact; a theoretically suitable material may be unavailable or inappropriate for the local workshop.
Sources for this lesson
Pause and explain
Which principle best supports this lesson: select materials and components for a purpose?
Worked example
A reusable outdoor sign needs a stiff, weather-resistant face that can be cut accurately. How would you compare two candidate materials?
Show the worked solution
- Set criteria for stiffness, weather exposure, dimensions, finish and available processes.
- Compare two named grades or stock forms using manufacturer or test data.
- Make a representative sample and evaluate cutting, durability and end-of-life.
Answer A suitable choice depends on the exact grade, thickness, support, weather and process. Compare property data and test a representative sample; do not assume all plastics or metals perform alike. Include sourcing, finish, maintenance and disposal in the decision.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Choose a material family for a lightweight model casing that needs repeated shaping. State what must be checked before committing.
Give me a hint
Compare workability with intended use, available stock and safety guidance.
Compare my reasoning
- Clarify whether the casing is a model or a product in use.
- Compare candidate materials for shaping method, mass and required detail.
- Check stock form, safety, cost, finish and environmental impact.
A modelling foam, card or suitable thermoplastic might be considered, depending on the detail and reuse needs. Check the exact stock form, tools, ventilation or heat risks, surface finish and whether the model must carry loads. The material choice is conditional on those requirements.
Look for these in your work
- Uses the design context
- Compares candidates
- Names safety and availability checks
A metal part must flex repeatedly without permanent bending. Which material properties and evidence matter?
Give me a hint
Separate elastic recovery from ductility and fatigue behaviour.
Compare my reasoning
- Describe the expected load and number of cycles.
- Check elastic behaviour, fatigue performance and corrosion resistance for the exact alloy.
- Test a sample under representative safe loading or use reliable engineering data.
Elastic recovery and fatigue resistance matter, along with the part's geometry and corrosion environment. Ductility describes deformation before fracture but does not alone predict repeated spring performance. Use grade-specific data and suitable testing.
Look for these in your work
- Distinguishes relevant properties
- Specifies grade and context
- Plans evidence rather than guessing
A biodegradable polymer is proposed for a reusable outdoor product. What questions test whether the choice is suitable?
Give me a hint
Check service life, environment, certification, disposal route and comparative impact.
Compare my reasoning
- Define required durability and environmental exposure.
- Check material data and conditions needed for biodegradation.
- Compare expected service life and actual local disposal with alternatives.
Verify the exact polymer, durability outdoors, additives, certified conditions for breakdown and available disposal route. If it must last many years, premature degradation may be a failure; if no suitable composting route exists, the expected end-of-life benefit may not occur.
Look for these in your work
- Checks exact material
- Considers use and disposal conditions
- Avoids assuming biodegradable means harmless
Common mistakes
- Using a material family name as if every grade has identical properties
- Calling a material sustainable from one property
- Confusing a smart material with a generic modern material
What can you explain now?
What should support a material choice for a load-bearing part?
Compare with the explanation
Relevant property and test evidence for the actual grade and form
Performance depends on grade, form, geometry, processing and loading; specify and test the real selection.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Name four material properties and link each to one product requirement.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.