Solids, Liquids & Gases
KindergartenThree ways matter likes to be
Matter usually shows up in one of three forms, called states:
- Solid — keeps its own shape, like a block, a toy, or an ice cube. You can hold it and it stays the same shape.
- Liquid — pours and takes the shape of whatever holds it, like juice in a cup. Pour it into a different cup and it changes shape to fit.
- Gas — spreads out to fill all the space it can, like the air in a balloon. You can't hold a gas in your hand — it just drifts away.
The same matter can even change between these states! Water is a great example: as ice it's a solid, as water it's a liquid, and as steam it's a gas.
It's all about how the tiny bits move
Remember the atoms from the last chapter? In a solid, the tiny bits are packed close together and barely move — like kids standing shoulder to shoulder in a line, holding hands tight, so the shape stays the same. In a liquid, the bits are still close but can slide past each other — like kids holding hands loosely, able to shuffle around while still bunched together. In a gas, the bits zoom around far apart from each other — like kids running wild all over a big playground.
That's why a solid holds its shape, a liquid flows and settles at the bottom of its container, and a gas spreads out to fill an entire room.
Try it — sort your own solids, liquids and gases
- Ask a grown-up to help you gather: an ice cube, a cup of water, and a balloon full of air.
- Touch the ice cube. It keeps its shape in your hand — that's a solid.
- Pour the water from one cup into another. It changes shape to match the cup — that's a liquid.
- Squeeze the balloon gently. The air inside spreads to fill every corner of it — that's a gas.
- Watch the ice cube over the next hour. What state does it turn into as it warms up?
Why does a liquid change shape when you pour it, but a solid doesn't?
In a solid, the tiny bits are locked close together and can't slide around, so the shape stays fixed. In a liquid, the bits can slip past one another, so the whole thing flows and takes the shape of its new container.
Is smoke a solid, liquid or gas?
Smoke behaves like a gas — it spreads out and fills the space around it, drifting and mixing into the air rather than keeping one shape.
Name one state of water at each temperature: very cold, room temperature, and boiling hot.
Very cold water is ice, a solid. Room-temperature water is a liquid. Boiling-hot water makes steam, a gas.
How the ideas connect
Every key idea in this chapter, branching from the core concept — use it to see the whole picture at a glance.
The key facts, visualised
Worked problems, step by step
Follow each solution line by line, then try to reproduce it on paper before moving on.
Example 1You pour juice from a bottle into a cup. Is juice a solid, liquid or gas?
- A solid keeps its shape and cannot pour.
- Juice flows and takes the shape of the cup.
- Matter that pours and fills a container is a liquid.
Example 2Why does the smell of cake spread across a whole room?
- The smell is made of gas bits from the cake.
- Gas bits move fast and spread out in every direction.
- They fill the room until you can smell them far away.
Now you try
Work each one out first, then tap to reveal the worked answer.