ACARA v9 CONTENT DESCRIPTION “examine the properties of natural and made materials including fibres, metals, glass and plastics and consider how these properties influence their use”
Builds on sorting everyday objects by what you can see and feel. Here we look closely at what materials are made of, test their properties, and find out why a property decides where each material is used.
Materials can be natural or made
Everything around you is built from materials. Some materials are natural, which means they come from living things or from the earth. Wool and cotton are natural fibres, and wood comes from trees. Other materials are made by people. Plastic is made from oil, steel is a metal made from iron, and glass is made from melted sand. Fibres, metals, glass and plastics are four big groups of materials you meet every day.
Sort the materials: natural or made
Pick a material, then send it to the natural tray or the made tray. Natural comes from living things or the earth; made is built by people.
Wool and cotton are natural fibres, and wood is a natural material. Plastic, steel and glass are made materials: steel is a metal, glass is made from sand, and plastic is made from oil.
Every material has properties you can test
A property is something about a material that you can observe and test. Some materials are flexible and bend easily, while others are rigid and stay straight. Some are transparent and let light through, and some are opaque and block it. Some are waterproof, so water beads on top, and some are absorbent and soak the water up. Testing a material tells you which properties it really has, instead of just guessing.
Test a material for a property
Pick a material, then run a test. Bending shows flexible or rigid, light shows transparent or opaque, water shows waterproof or absorbent.
A property is something you can test and observe. The same material can be flexible or rigid, transparent or opaque, waterproof or absorbent. Testing tells you which properties a material has, instead of just guessing.
Properties point to the right job
Once you know the properties of a material, you can match them to a job. A window needs to be transparent so you can see through it and rigid so it holds its shape, which is why windows are made of glass. A raincoat needs to be waterproof to keep the rain off and flexible so it bends with you, which is why raincoats are made of plastic.
Match the property to the use
Each job needs a pair of properties. Reveal the material whose properties fit the job.
Pick a job, then show the match to see why those properties point to one material.
Comparing materials to pick the best one
For many jobs more than one material could work, so you compare them and choose the best fit. A drink bottle should hold water, let you see the drink and be light to carry. Plastic fits all three, paper soaks up the water, and steel is heavy and you cannot see through it. Comparing the properties helps you choose well.
Choose the best material for a drink bottle
A drink bottle should hold water, let you see the drink and be light to carry. Compare three options and find the one that fits.
Best fit: waterproof, see-through and light to carry.
How a property influences its use
The way a material behaves is what decides where it is used. A spoon is made of metal because metal is strong and stiff, so it keeps its shape and lifts the food. A handle is often covered in rubber because rubber grips your hand and does not slip. Change the property and the use no longer fits, which shows that the property leads to the use.
A property decides where a material fits
A spoon must stay stiff to lift food. Toggle the material between strong and weak to see why the property decides the use.
A spoon is usually made of metal because metal is strong and stiff, so it holds its shape and lifts the food. A weak, floppy material would droop and spill. The property of the material is what decides whether it suits the job.
Why this matters
Looking at why things are made of what they are made of helps you make sense of the world. You can see why pipes are metal, why bags are plastic and why drinking glasses are glass. Knowing how the properties of natural and made materials influence their use sets you up for more science about materials and how they change later on.
Quick self-check
1. Which list shows only natural materials?
2. You bend a material and it stays straight. Which property does it have?
3. A window needs to be transparent and rigid. Which material fits best?
4. Why is plastic a good choice for a drink bottle but paper is not?
5. A metal spoon stays stiff when it lifts food. What does this tell you?