Grade 3 (age 8-9)

Properties of Liquids and Solids

The materials around us sort into solids, liquids, and gases. Wood and ice keep their shape, so they are solids, while water fits the shape of any container, so it is a liquid. The same water freezes into solid ice and boils into gas as vapor. Watch the particle model and pour water into different cups to see how solids and liquids differ.

Three States of Matter

🔬 Matter through Particles

①Solid: particles tightly packed, vibrating in place

②Liquid: close particles that move freely

③Gas: particles spread out, flying very fast

Liquids — shape changes

💧 Properties of Liquids

①Shape depends on the container

②But volume stays the same

③Surface is always level

④Flows easily

Solids — shape stays

🧊 Properties of Solids

①Shape stays no matter the container

②Hard when pressed

③Has a fixed shape and volume

④Can be stacked

Summary

Properties of Solids

Solid = fixed shape + fixed volume

Particles tightly and regularly arranged

Properties of Liquids

Liquid = changing shape + fixed volume

Close particles that move freely

Properties of Gases

Gas = changing shape + changing volume

Particles spread out and move freely

🎯 Key Points

①Solid: fixed shape and volume

②Liquid: shape changes, volume fixed

③Gas: shape and volume both change

④Same substance can change state with temperature

⑤Water: ice(solid)→water(liquid)→vapor(gas)

Examples and Unit Test

Example 1

If you pour 200 mL of water from a wide bowl into a narrow cup, what happens to its shape and amount?

A liquid changes its shape depending on the container it is poured into.

But the amount (volume) of a liquid does not change, so it takes the shape of the cup while the amount stays 200 mL.

▸ The shape changes, but the amount (volume) stays 200 mL

A liquid changes shape with the container but keeps the same volume.

Example 2

When you move a wooden stick (solid) and water (liquid) into different containers, how does the shape of each change?

A solid keeps the same shape and volume even when the container changes.

A liquid keeps the same volume but changes shape with the container, so the wooden stick keeps its shape while the water takes the container shape.

▸ Wooden stick = same shape / water = takes the container shape

A solid keeps a fixed shape; a liquid changes shape with the container.

Unit-test style

Which statement about solids and liquids is correct?

①A liquid changes its amount (volume) when the container changes

②A solid keeps its shape even when the container changes

③A liquid keeps the same shape wherever you put it

④A solid changes shape depending on the container

⑤The water surface tilts when you tilt the container

▸ ② A solid keeps its shape even when the container changes

A solid has a fixed shape and volume, so it keeps its shape even when the container changes.

A liquid keeps the same volume when the container changes (①), only a liquid changes shape with the container (③ and ④), and the water surface stays level (⑤).

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Material Properties

Weight & Spring