Year 6 · Science · Chemical sciences
Solids, liquids and gases
Students compare the observable properties of solids, liquids and gases and show that gases, like air, take up space and have mass.
Awaiting educator review. This material was drafted by our content team with AI assistance and is waiting for review by a qualified educator. Please check it suits your child before using it. Created 10 October 2026.
These lessons were written around Australian Curriculum strands and matched to New Zealand year levels by age (NZ Year 1 is the first year of school). They are not yet mapped to The New Zealand Curriculum, so check them against your own learning programme.
Learning goals
Learners will
- Describe the properties of solids, liquids and gases.
- Show that air is a gas that takes up space.
- Classify everyday materials by their state.
Success looks like
- I can describe how solids, liquids and gases differ in shape and volume.
- I can show that air takes up space using a cup and water.
- I can sort materials into solids, liquids and gases.
The big idea
Everything around us is made of matter, and matter can be a solid, a liquid or a gas. These are called states of matter.
- Solids keep their own shape and volume. A brick stays brick-shaped wherever you put it.
- Liquids keep their volume but take the shape of their container. A cup of water poured into a bowl spreads out, but there is still a cupful.
- Gases have no fixed shape or volume. They spread out to fill any container. Air in a balloon fills the whole balloon.
Even though we cannot see most gases, they are real matter. Air takes up space and has mass. A pumped-up footy weighs very slightly more than a flat one.
Some materials are tricky. Sand pours like a liquid, but each grain is a tiny solid that keeps its shape. Toothpaste and honey are thick liquids or soft solids, and scientists sometimes argue about how to classify them.
Materials can change state. Water can be a solid (ice), a liquid (water) or a gas (water vapour). Puddles dry up after rain because the water evaporates into water vapour.
Worked examples
Air takes up space
Can you push a paper towel underwater in a cup without it getting wet?
- Scrunch a dry paper towel and push it firmly into the bottom of the cup.
- Turn the cup upside down and push it straight down into a bowl of water. Keep it level.
- Lift it straight back out and feel the paper towel.
- The paper towel is dry because air trapped in the cup took up the space and kept the water out.
Answer: Yes. Trapped air takes up space and stops water reaching the paper.
Classifying states
Classify: milk, a spoon, steam, honey, a rock, air.
- Ask: does it keep its shape? Spoon and rock do, so they are solids.
- Ask: does it flow and take the shape of its container but keep its volume? Milk and honey are liquids.
- Ask: does it spread to fill any space? Steam and air are gases.
Answer: Solids: spoon, rock. Liquids: milk, honey. Gases: steam, air.
Practice check
Have a go, then check your answers. Each answer comes with an explanation.
Answer guide for parents
Which state of matter keeps its own shape?
Solid — Solids keep their own shape and volume.
Which statement about liquids is true?
They take the shape of their container — Liquids flow and take the shape of their container but keep the same volume.
Why did the paper towel stay dry in the upside-down cup?
Air in the cup took up the space — Air is matter and takes up space, so water could not get in.
Sand can be poured. Why is it still classed as a solid?
Each grain keeps its own shape — Each sand grain is a solid that keeps its shape.
What happens to a puddle on a sunny day?
The water evaporates — The liquid water changes into water vapour, a gas.
Which state of matter spreads out to fill any container?
gas — Gases have no fixed shape or volume.
What is the gas form of water called? (two words: water ______)
water vapour — Water as a gas is water vapour.
Is orange juice a solid, liquid or gas?
liquid — Juice flows and takes the shape of its container.
Watch out for
- Many students think air is 'nothing'. Air is matter: it takes up space and has mass.
- Some think powders like flour or sand are liquids because they pour. Each grain is solid.
- Students may think steam is the white cloud above a kettle. Steam (water vapour) is invisible; the white cloud is tiny droplets of liquid water that have cooled.
Tips for parents
- Do the cup-and-paper-towel test over the sink or outdoors.
- Ask your child to justify each classification with a property: 'It is a liquid because…'.
- Safety: keep children away from boiling kettles; talk about steam from a distance only. Never put a balloon near the mouth of a young child.
Go further
- Stretch a balloon over the neck of an empty bottle and stand it in a bowl of warm tap water. The air inside warms, expands and the balloon starts to inflate.
- Draw particle pictures showing how tightly packed particles might be in a solid, liquid and gas.
- Mark the level of water in a glass left on a windowsill and check it each day for a week.