Year 3 Science · Chemical sciences · Learning & practice

The Science of Baking: Solids, Liquids and Melting

Discover how heat changes butter, batter and water from one state to another — and use that knowledge to predict what happens in a kitchen.

Section 1 · Observable properties

Solids and Liquids in the Kitchen

By the end of this section I can describe the observable properties of solids and liquids and sort baking ingredients by their state — so I can choose the right ingredient for the right job.

Success criteria 0 / 4 ticked

Tick each one when you can do it without help.

1A What makes a solid a solid?

A solid keeps its own shape. A block of butter, a sugar cube and a flour scoop all hold their shape whether you tip them sideways or leave them on the bench. The tiny particles inside a solid are packed tightly and can only vibrate in one spot.

Key properties of solids

keeps its own shape fixed volume does not pour particles packed tight

Try this in your mind: tip a sugar cube upside down. It lands as the same shape — that is the test for a solid. A solid does not flow to fill a container.

Is a chocolate button a solid?

1. Tip it upside down. Does it keep its shape?
2. Yes — it stays a small disc. It does not flow.
3. So a chocolate button is a solid. It keeps its own shape and fixed volume.

Check yourself

You drop a frozen scone onto the bench. It stays the same shape and does not spread out. What state of matter is the frozen scone?

Ask yourself: does it keep its own shape when tipped or dropped?
The frozen scone keeps its shape and has a fixed volume, so it is a solid.

1B What makes a liquid a liquid?

A liquid takes the shape of its container. Milk poured into a jug looks like a jug; the same milk poured into a bowl looks like a bowl. But the amount of milk — its volume — does not change. The particles in a liquid are close together but can slide past one another, so a liquid flows.

Key properties of liquids

takes the shape of its container fixed volume flows and pours particles slide past each other

Honey is a tricky one. It flows slowly, but it still flows and takes the shape of its jar — so honey is a liquid, just a very thick one.

Interactive · sort the baking ingredients

Tap each ingredient, then tap a bin to place it. Sort all eight, then check your work.

Solids
Liquids
Placed: 0 / 8

Check yourself

You pour golden syrup from a tin into a spoon. It flows and fills the shape of the spoon. What state of matter is golden syrup?

Does it flow and take the shape of its container?
Golden syrup flows and takes the shape of the spoon, so it is a liquid.

A bag of self-raising flour sits on the bench. Even though the grains are tiny, the flour as a whole keeps its pile shape and does not flow on its own. What state is the flour?

Each grain keeps its shape and the pile does not flow to fill a container by itself.
The flour grains keep their shape and the flour sits in a pile, so it is a solid — a powder is still a solid.

Section 2 · Change of state

Heating, Cooling and Change of State

By the end of this section I can explain how adding or removing heat energy changes a material from solid to liquid to gas — so I can predict what happens to baking ingredients in the oven or the fridge.

Success criteria 0 / 4 ticked

Tick each one when you can do it without help.

2A Adding heat energy: melting and boiling

When you add heat energy to a solid, its particles gain energy and start to move more. At a certain temperature they break free from their fixed spots and the solid becomes a liquid — this is called melting. Add even more heat and the liquid becomes a gas — this is called boiling.

Key vocabulary

heat energy melting — solid → liquid boiling — liquid → gas evaporating

Butter melts at about 32 °C. Water boils at 100 °C. Different substances melt and boil at different temperatures because their particles are held together with different strength.

Butter on a warm pan

1. Start: cold butter is a solid. Particles are packed and fixed in place.
2. Add heat from the pan. Particles gain energy and vibrate more.
3. At 32 °C the butter melts into a liquid. Particles can now slide past each other.
4. If heated far more, some butter evaporates. Particles escape into the air as a gas.

Interactive · drag the temperature and watch the particles

Move the temperature slider from cold to hot. Watch the water particles change arrangement and read the state.

0 °C
Solid (ice)
0 °C306090120 °C
State: solid (ice) · No change yet — add heat!

Check yourself

You leave a block of cooking chocolate on a hot car seat in summer. What change of state happens to the chocolate?

Adding heat energy to a solid turns it into a liquid. What is that called?
The chocolate is a solid. Heat energy makes its particles move and break free, so it melts into a liquid.

You heat a saucepan of water for pasta. At 100 °C bubbles rise and steam appears. What change of state is happening to the water?

A liquid turning into a gas at its top temperature has a special name.
At 100 °C the liquid water gains enough heat energy to become a gas, so it boils.

2B Removing heat energy: freezing and the baking swap

Removing heat energy does the reverse. A liquid becomes a solid when it loses enough heat — this is called freezing (or solidifying). In baking, cake batter is a runny liquid, but in the oven it turns into a firm solid cake. The heat drives the change, not the cold.

Key vocabulary

freezing — liquid → solid condensing — gas → liquid solidifying

Wait — batter becomes cake in a hot oven, not a cold fridge. The heat causes chemical changes that build a solid structure from the liquid batter. Cooling a baked cake then sets that structure firm.

Melted butter back to the fridge

1. Start: melted butter is a liquid in the bowl. Particles slide freely.
2. Place bowl in the fridge. Heat energy is removed.
3. Below 32 °C the butter freezes back to a solid. Particles lock into place again.

Check yourself

You pour melted butter into a mould and put it in the freezer. What change of state happens as the butter loses heat energy?

A liquid losing heat energy and becoming a solid has a familiar name — think winter puddles.
The liquid butter loses heat energy, so its particles slow and lock in place. It freezes into a solid.

After baking, a muffin is firm and holds its shape. You can pick it up and it does not flow. What state of matter is the baked muffin?

Does it keep its own shape when you pick it up?
The baked muffin keeps its own shape and fixed volume, so it is a solid.

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