Chapter 3 · Primary 3 Science
Diversity of Materials
📚 Section A — Revision Notes
🎯 What I Will Learn
- What are some materials around us?
- What are some properties of materials?
- How are materials chosen to make an object?
1
What Are Some Materials Around Us?
- Things around us are made of different materials.
- Some materials are found in nature. Others are made by humans.
- Examples: wood, metal, ceramic, rubber, glass, plastic and fabric.
| Material | Source | Used to make |
|---|---|---|
| Wood | Trees | Houses, furniture, boats, paper, pencils |
| Metal (gold, silver, iron, copper, aluminium) | The ground | Jewellery, wires, aircraft, cooking pots, drink cans |
| Ceramic | Clay from the ground | Vases, plates, bowls, bricks |
| Rubber | Sap of rubber tree, or made from oil | Tyres, erasers, raincoats, rubber bands |
| Glass | Sand | Windowpanes, spectacle lenses, light bulbs, mugs |
| Plastic | Made by humans using oil from the ground | Plastic bags, bottles, toys, containers |
| Fabric (wool, silk, cotton) | Plants or animals | Clothes, towels, soft toys |
2
What Are Some Properties of Materials?
- The physical property of a material is something about it that can be observed or measured.
- We can compare materials using their physical properties.
Strength
Ability to be pushed, pulled or dropped without breaking
Strong: metal · Fragile: ceramic
Flexibility
Ability to bend without breaking
Flexible: plastic · Rigid: wood
Float or Sink
Whether the material floats on or sinks in water
Floats: wood · Sinks: metal
Waterproof or Not
Whether the material absorbs water or repels it
Waterproof: metal, rubber, glass, plastic
Transparency
How much light can pass through the material
Transparent: glass · Translucent: frosted glass · Opaque: wood
💡 Memory Trick — Mnemonic
School Trip With Funny Friends
S
Strength
T
Transparency
W
Waterproof or not
F
Flexibility
F
Float or sink
💪 Strength
- Strength = ability to be pushed, pulled or dropped without tearing or breaking.
- Strong materials will not break easily when pushed, pulled or dropped.
- Weak / fragile materials will break easily when pushed, pulled or dropped.
- Metal is strong — it does not break easily. Ceramic is fragile — it breaks easily when dropped.
Exam Tip — Strong vs Rigid
A material may be strong but not rigid (e.g. plastic — it is strong but flexible).A material may be rigid but not strong (e.g. ceramic — it is rigid but fragile/weak).
Strong = hard to break. Rigid = hard to bend. These are different properties!
🔄 Flexibility
- Flexibility = ability to bend without breaking.
- Flexible materials bend easily without breaking (e.g. plastic).
- Rigid materials will not bend easily without breaking (e.g. wood).
- Plastic is more flexible than wood — plastic bends easily, but wood breaks when bent.
🌊 Ability to Float or Sink
- Some objects float on water. Others sink in water.
- The material of an object affects whether it floats or sinks.
- A wooden ball floats on water. A metal ball sinks in water.
Good to Know
Objects made of the same material may float or sink. A small metal coin sinks in water. However, a large ship made of metal floats — because the ship has a lot of air inside, which helps keep it afloat.
💧 Ability to Absorb Water
- Some materials absorb water and allow it to pass through them.
- Other materials do not absorb water — these are called waterproof materials.
| 💧 Not Waterproof (absorbs water) | 🛡️ Waterproof (repels water) |
|---|---|
| Wood, fabric | Metal, rubber, glass, plastic |
🔆 Transparency
- Transparency = how much light can pass through the material.
Transparent
Allows most light to pass through — we can see through it clearly
Glass, some plastics
Translucent
Allows some light to pass through — we cannot see through clearly
Frosted glass, thin fabric, some plastics
Opaque
Allows no light to pass through — we cannot see through at all
Wood, metal, ceramic, rubber
Get It Right!
✗ Wrong
Transparent materials allow all light to pass through them.
✓ Correct
Transparent materials allow most light to pass through them. If all light could pass through, we would not be able to see the material at all.
📋 Checkpoint 3.1
1. Name three properties of materials.
Any three from: strength, flexibility, ability to float or sink in water, ability to absorb water (waterproof or not), transparency.
Mnemonic: School Trip With Funny Friends
Mnemonic: School Trip With Funny Friends
🧪 Fair Test
- We compare properties of materials by testing them.
- In a fair test, only one variable is changed at a time.
- Taking measurements carefully makes results accurate.
- Repeating the experiment a few times makes results reliable.
🔬 Example — Testing which material absorbs more water
Variable changed:Type of material (material A vs material B)
Variables kept same:Size of strip, thickness of strip, amount of water, length dipped, time dipped
Variable measured:Amount of water remaining in the beaker
The beaker with less water remaining has the material that absorbs more water.
⚙️ Worked Example 3.1 — Ranking Materials by Strength
Four strips of equal thickness and length were hung with weights until they broke.
Arrange the materials starting with the strongest.
| Material | A | B | C | D |
| Weights until broke | 4 | 7 | 3 | 5 |
Arrange the materials starting with the strongest.
How to solve: More weights needed to break = stronger material.
B(7) > D(5) > A(4) > C(3)
Answer (strongest → weakest): B → D → A → C
B(7) > D(5) > A(4) > C(3)
Answer (strongest → weakest): B → D → A → C
3
How Are Materials Chosen to Make an Object?
- Objects have different purposes. The material chosen depends on the properties of the material and the purpose of the object.
- The same object can be made of different materials (e.g. a spoon can be metal or plastic).
- Some objects have many parts with different functions — different materials are used for each part.
| Object | Material | Properties that make it suitable |
|---|---|---|
| Clothes | Fabric | Flexible |
| Rain boots | Rubber | Flexible and waterproof |
| Windowpane | Glass | Transparent and waterproof |
| Water bottle | Plastic | Strong and waterproof |
| Chair | Wood | Strong and rigid |
| Spoon | Metal | Strong, rigid and waterproof |
Good to Know
Sometimes different materials are mixed together to create a new material with better properties. For example, steel is made by mixing iron with a substance called carbon. Steel is stronger than iron and does not rust as easily.
📋 Checkpoint 3.2
1. State two properties of the material used to make a raincoat.
A raincoat is made of rubber (or plastic). The properties are:
1. Flexible — allows the wearer to move freely.
2. Waterproof — does not absorb water, keeping the wearer dry.
1. Flexible — allows the wearer to move freely.
2. Waterproof — does not absorb water, keeping the wearer dry.
⚡ Chapter Summary
- 7 common materials: wood, metal, ceramic, rubber, glass, plastic, fabric.
- 5 physical properties: strength, transparency, waterproof or not, flexibility, float or sink (School Trip With Funny Friends).
- Strong ≠ rigid. Strong = hard to break. Rigid = hard to bend (these are different!).
- Transparent = most light, translucent = some light, opaque = no light.
- Fair test: change one variable only; results should be accurate and reliable.
- Materials are chosen based on their properties and the purpose of the object.
- The same object can be made of different materials. Objects with many parts may use different materials for each part.
✏️ Test Yourself
1. Meilin wants to make a hat that will protect her head from rain and sunlight. Which properties should the material have?
A — It should be flexible.
B — It should be opaque.
C — It should be waterproof.
D — It should float on water.
A — It should be flexible.
B — It should be opaque.
C — It should be waterproof.
D — It should float on water.
2. A student drops a metal cup and a ceramic cup from the same height. State what happens to each cup and explain why.
The metal cup will not break — metal is strong and does not break easily when dropped.
The ceramic cup will break — ceramic is fragile (weak) and breaks easily when dropped.
The ceramic cup will break — ceramic is fragile (weak) and breaks easily when dropped.
✏️
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