C. Matter and Energy · Properties of and Changes in Matter

Describing Matter: Properties of Solids, Liquids and Gases

C2.2 A1.2 A1.4 A1.5About 40 minutes

Learning goals

I can describe matter using properties like hardness, flexibility, texture and lustre.
I can compare how easily liquids flow (viscosity).
I can describe properties of gases.
I can plan and carry out a fair test and share my results.

Words to know

property
Something about a material that you can observe or measure, like its colour, hardness or how easily it flows.

hardness
How well a solid resists being scratched or dented.

flexibility
How easily a solid bends without breaking.

lustre
How shiny a material is.

viscosity
How thick a liquid is, or how slowly it flows. Honey has a high viscosity. Water has a low viscosity.

fair test
An experiment where you change only one thing and keep everything else the same.

Describe it without naming it

Can you guess this mystery object? It is a solid. It is hard, shiny and smooth. It is stiff, not bendy. It sinks in water and a magnet sticks to it.

It could be a steel spoon! You just used properties to describe matter. Scientists use properties to describe, compare and choose materials.

Properties of solids

Solids have properties you can see, feel and test:

colour (red, clear, white)
texture: how it feels (smooth, rough, soft, bumpy)
lustre: how shiny it is (shiny or dull)
hardness: how well it resists scratches and dents (a rock is hard, butter is soft)
flexibility: does it bend? (an elastic band bends and stretches; a pencil snaps)
strength: does it hold weight without breaking?
magnetic or not: does a magnet stick to it?
floats or sinks in water
absorbs water or repels it (a sponge soaks it up; a raincoat keeps it out)

Object	Hardness	Flexibility	Lustre	Other properties
steel spoon	hard	stiff	shiny	a magnet may stick to it; sinks
elastic band	soft	very flexible, stretchy	dull	springs back to its shape
wooden ruler	fairly hard	bends a little	dull	floats
aluminium foil	soft	very flexible	shiny	a magnet does not stick

Describing solids by their properties. (A magnet sticks to some steel spoons but not others, depending on the kind of steel, so test yours!)

Properties of liquids

Liquids have properties too:

viscosity: how thick a liquid is, or how slowly it flows. Water flows quickly (low viscosity). Honey and maple syrup flow slowly (high viscosity).
colour and clearness: water is clear, milk is not.
smell
does it mix with water? Juice mixes with water. Cooking oil does not: it floats on top in a layer.
does it float or sink in water? Oil floats on water. Maple syrup sinks to the bottom.

A glass jar holding clear water on the bottom and a layer of yellow cooking oil floating on top. — Oil and water do not mix. The oil floats on the water in its own layer, which is one of the properties scientists use to describe liquids. AI-generated image

Poured gently into a clear glass, maple syrup sinks to the bottom, cooking oil floats on top, and water stays in between. (Over time the syrup slowly mixes into the water, but the oil stays separate.)

Properties of gases

Gases spread out to fill any space.
Gases can be compressed (squeezed).
Most gases are colourless and invisible, like air.
Some gases have a smell. Natural gas for stoves and furnaces has no smell of its own, so a strong smell is added to it on purpose, so people can notice a leak.
Some gases are lighter than air, like the helium in a balloon that floats up. Some are heavier than air, like carbon dioxide.

Worked example

Let's read a fair test: the viscosity race

Maya wondered: Which liquid flows fastest? She put 1 teaspoon each of water, cooking oil, maple syrup and honey in a row at the top of a tilted baking sheet. She let go of all of them at the same time and timed how long each took to reach a finish line 20 cm away.

water: 2 seconds
cooking oil: 6 seconds
maple syrup: 25 seconds
honey: 70 seconds

What did she change? Only the kind of liquid.
What did she keep the same? The amount (1 teaspoon), the starting line, the distance (20 cm), the tilt of the sheet and the room temperature. It was a fair test.
Order the results, fastest to slowest: water, oil, maple syrup, honey.
Slowest flow means highest viscosity.

Water has the lowest viscosity and honey has the highest. From least to most viscous: water, cooking oil, maple syrup, honey.

Maya's viscosity race as a bar graph. The longest bar took the most time, so honey has the highest viscosity; water has the lowest.

Fair test check

A fair test changes only one thing. If Maya had used a whole tablespoon of honey but only a teaspoon of water, or tilted the sheet more for one liquid, her race would not be fair.

Just for fun

Why did the magnet have so many friends?

It had a very attractive personality! (But only to some metals: a magnet doesn't stick to aluminium foil.)

Hands-on activity

The great liquid race

You need: a baking sheet or a large plastic cutting board, a book to tilt it, masking tape, a ruler, a teaspoon, 4 liquids from the kitchen (for example water, cooking oil, maple syrup or pancake syrup, honey or ketchup), a timer, paper and pencil.

Question: Which liquid flows fastest?
Predict: put the liquids in order from fastest to slowest.
Put tape across the sheet for a start line, and another 20 cm lower for a finish line.
Put 1 teaspoon of each liquid on the start line, a few centimetres apart, while the sheet is flat.
Prop up one end of the sheet on the book and start the timer. Record when each liquid crosses the finish line. (Stop after 3 minutes if one hasn't finished.)
Record your results in a table. Then repeat the race to check.
Conclude: Which liquid has the highest viscosity? Was your prediction right?
Share your results with someone at home. Use the words viscosity and fair test.

What to look for: watery liquids win; thick liquids like honey and ketchup are slowest.

Safety: these are kitchen liquids, but in a science test we don't taste anything. Wash the sheet and your hands when you finish, and wipe up drips so nobody slips.

Your turn

What is a property?

Name three properties of solids.

What does viscosity describe?

Which has a higher viscosity: water or honey?

Name two properties of gases.

In Maya's race, which liquid had the lowest viscosity?

More practice: warm-up

Shiny or dull: aluminium foil?

Flexible or stiff: an elastic band?

Hard or soft: a rock?

Does cooking oil mix with water?

Does a helium balloon float up or sink down in air?

More practice: on your own

Describe a wooden ruler using at least three properties.

Why do you think natural gas has a smell added to it?

Ben tested how fast water and honey flow. He used 1 teaspoon of water and 3 teaspoons of honey. Was it a fair test? Why?

Maple syrup took 25 s and cooking oil took 6 s in Maya's race. How much longer did the syrup take?

Why do we repeat a test?

Challenge

Maya warms the honey jar in a bowl of warm tap water (with a grown-up's help) and races it again. It wins against cold honey. What does that tell you about viscosity?

A mystery liquid is clear and colourless, has no smell, flows fast and sinks below a layer of cooking oil. Is it more likely water or maple syrup? Explain.

Design a fair test to find out which of three paper towel brands soaks up the most water. What will you change, keep the same and measure?

Check your understanding

Quiz

Viscosity describes...

Which liquid has the highest viscosity?

A material that bends easily without breaking is...

Lustre describes...

Which is a property of most gases?

In a fair test of which liquid flows fastest, you should change...

For parents and teachers

Big idea: This lesson continues C2.2: describing characteristics and properties of solids, liquids and gases. The liquid race is a fair test (A1.2), done safely (A1.4), with results shared (A1.5).

How to help: Describe household objects with property words and play "Guess my object". Ask "What did you change? What did you keep the same?" about any test.

Common difficulties:

Using only colour and size. Prompt with hardness, flexibility, lustre, texture.
Thinking heavy liquids are always thick. Viscosity is about flow, not just how heavy the liquid feels.
Changing two things in a test. Check the amount, start line and tilt together.

Safety: no tasting during science tests. Wipe up sticky spills. Only a grown-up should handle anything warm.