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IB Design Technology
SL · Lesson 35 · How Designers Classify Materials
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Lesson 35 · Unit 5

How Designers
Classify Materials

Build a material vocabulary that lets designers compare options by properties, origin and structural use.

80 minutesA3.1.1–A3.1.3
Guiding question: How do classifications help designers narrow a complex material-selection problem?01
Today’s destination

By the end of class, you should be able to…

01

Explain classification

Describe why designers group materials by properties.

02

Classify by origin

Distinguish natural and human-made material families.

03

Recognize structure types

Frame, shell, solid and combination.

04

Connect to selection

Use classifications to narrow a material decision.

Success check: Explain the concept accurately, then use it to make a justified design decision.
A3.1 · classification is a decision tool02
3
A3.1.1

Properties give designers three lenses.

P

Physical

Measured/observed without chemically changing the material.

C

Chemical

How the material reacts chemically with other substances or conditions.

M

Mechanical

How the material responds when forces are applied.

A3.1.1 · physical / chemical / mechanical03

Compare

Use common property language across different materials.

Filter

Eliminate unsuitable candidates early.

Communicate

Give teams a shared technical vocabulary.

Justify

Link a final choice to measurable/observable requirements.

Classification does not automatically pick the “best” material. Context and trade-offs still matter.
Classification organizes complexity04
A3.1.2

Materials can also be grouped by where they come from.

Natural

Derived from natural sources

Examples can include timber and natural fibres. They may still be processed before use.

↔
Human-made

Engineered / manufactured by people

Examples include many polymers, glasses, composites and engineered smart materials.

A3.1.2 · source/origin05

Timbers

Natural or engineered wood products.

Polymers

Large-molecule materials with wide property ranges.

Metals

Metallic materials/alloys selected for specific properties.

Glass

Amorphous inorganic material with optical and structural uses.

Core families · recognition before selection06

Textiles

Flexible structures made from fibres/yarns; properties depend on fibre and construction.

Composites

Two or more materials combined to enhance performance.

Smart materials

Properties change significantly in response to environmental stimuli.

Biomaterials

Biologically derived / compatible materials; important to future circular strategies.

A3.1.2 · required categories07
A3.1.2 also names structural forms

Frame, shell, solid and combination describe how material is arranged.

Frame

Members create a skeleton that carries loads; much of the volume is empty.

Shell

A thin outer skin/enclosure provides form and carries load.

Solid

Material occupies most of the volume; mass itself resists forces.

Combination

Two or more structural approaches are used together.

Do not confuse material family with structural form08
Knowledge check

A bicycle primarily uses tubes joined into a load-carrying skeleton. What structural form is this?

A3.1.2 · frame / shell / solid / combination09
A3.1.3

“Strong” is not a complete material specification.

FunctionWhat must the product do?
Forces / environmentWhat conditions act on it?
PropertiesWhat physical, chemical, mechanical responses matter?
AestheticsTexture, form, colour, perceived quality.
Trade-offWhich combination is most appropriate?
A3.1.3 · identify the most suitable material10

Reusable lunch container

The product must be lightweight, food safe, resistant to repeated washing, visually acceptable and durable.

Ask first

Which requirements are physical? chemical? mechanical? aesthetic?

Then

Which material families are worth investigating—and which can you eliminate?

Classification turns a vague choice into searchable criteria11
Terminology retrieval
Tap to reveal
Physical property
Meaning
A measurable/observable aspect of a material without changing it chemically.
Tap to reveal
Chemical property
Meaning
An aspect involving chemical reaction with another substance or condition.
Tap to reveal
Mechanical property
Meaning
An aspect of material behaviour under an applied force.
Tap to reveal
Combination structure
Meaning
A product structure using more than one structural form, such as frame + shell.
A3.1.1–2 · core terminology12
Why is classifying materials useful if designers still need to evaluate trade-offs?
Classification creates a consistent way to compare/filter options; it reduces complexity but does not replace context-specific judgement.
Name the eight material categories explicitly listed in A3.1.2.
Timbers, polymers, metals, glass, textiles, composites, smart materials and biomaterials.
Why can two products made from the same material still have different structural classifications?
Structure describes how material is arranged—frame, shell, solid or combination—not what the material itself is.
Retrieval · classification + structure13
Exit ticket

Before you leave…

1. Classify one classroom material by source/origin.
2. Name one relevant physical, chemical or mechanical property for that material.
3. Identify whether one nearby product uses a frame, shell, solid or combination structure.
Next lesson

Material Properties

Keep the evidence chain moving: user → research → decision → test.

Curriculum alignment
A3.1.1–3.1.3: classify materials by physical, chemical and mechanical properties; classify by source/origin as natural and human-made including timbers, polymers, metals, glass, textiles, composites, smart materials and biomaterials; discuss frame, shell, solid and combination structures; evaluate properties/aesthetic characteristics when identifying suitable materials.
Lesson complete14 slides
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IB Design Technology SL · Lesson 3514