States of Matter & the Water Cycle (KS2)

SC9States of Matter and the Water Cycle

Solid, liquid, gas — and water's grand tour.

Matter exists in three states; heating and cooling change between them, driving the water cycle.

The three states.

🧊 Solid
Fixed shape, particles packed tightly.

💧 Liquid
Flows, takes the shape of its container.

☁️ Gas
Spreads to fill all the space.

Heat adds energy (melt, evaporate); cool removes it (condense, freeze).

Learn the Changes

1Heating changes state upward.

Solid → liquid is MELTING; liquid → gas is EVAPORATING (or boiling). Adding heat gives particles more energy.

melt · evaporate

2Cooling changes state downward.

Gas → liquid is CONDENSING; liquid → solid is FREEZING. Removing heat slows the particles.

condense · freeze

3The water cycle uses both.

Sun evaporates water from seas → it condenses into clouds → falls as rain → flows back to the sea. A never-ending loop.

💡 Key IdeaChanging state is reversible — the water is still water whether ice, liquid or vapour. Only the arrangement of particles changes.

Worked Example

Why do water droplets form on the outside of a cold glass on a warm day?

Warm air

air holds invisible water vapour (a gas)

→

Cold glass

cools the air touching it

→

✓ Condensation

vapour condenses into liquid droplets on the glass

Watch Out! Common Mistakes

‘The droplets leaked through the glass.’

Condensation! The water comes from vapour in the AIR condensing on the cold surface — not from inside the glass.

‘Evaporation only happens when boiling.’

Not just boiling! Water evaporates slowly at any temperature — that’s how puddles dry up and washing dries.

Melting vs dissolving.

Different! Melting is heating a solid into a liquid. Dissolving is a solid mixing into a liquid (sugar in tea) — no heat needed.

⬇ Cheat Sheet

STATES OF MATTER AND THE WATER CYCLE

Three states: solid, liquid, gas.
Heating: melt (solid→liquid), evaporate (liquid→gas).
Cooling: condense (gas→liquid), freeze (liquid→solid).
Water cycle: evaporate → condense → rain → repeat.

Example: cold glass → air's vapour condenses → droplets.

📖 Continue Your Journey

✓ SC1 Classifying Living Things ✓ SC2 Habitats and Adaptation ✓ SC3 Food Chains and Webs ✓ SC4 The Skeleton and Muscles ✓ SC5 Digestion and Teeth ✓ SC6 The Circulatory System ✓ SC7 Plants and Photosynthesis ✓ SC8 Life Cycles and Reproduction SC9 States of Matter and the Water Cycle SC10 Materials and Their Properties SC11 Reversible and Irreversible Changes SC12 Forces and Magnets SC13 Light and Shadows SC14 Sound SC15 Electricity and Circuits SC16 Earth and Space

→

Next Lesson: SC10 Materials and Their PropertiesChoosing the right stuff for the job.

📄 Free printable: Download the States of Matter and the Water Cycle cheat sheet (PDF) — keep it by your child's desk.

Quick summary

Matter has three states: solid, liquid, gas.
Heating melts and evaporates; cooling condenses and freezes.
Changes of state are reversible — it's still the same substance.
The water cycle: evaporation → condensation → precipitation → repeat.

Frequently asked questions

What are the three states of matter?

Solid (fixed shape), liquid (flows and takes its container's shape) and gas (spreads to fill all the space).

What drives the water cycle?

The Sun evaporates water from seas and lakes into vapour; it cools and condenses into clouds, then falls as rain and flows back — an endless loop.

Why does water form on a cold glass?

Water vapour in the warm air condenses into liquid droplets when it touches the cold surface — the water comes from the air, not through the glass.

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