Kitchen science for kids: experiments with eggs, flour and ice

The kitchen is the nearest laboratory in your home. It has water, it has cold, it has food that changes shape and texture, and there is usually a grown-up close by. You don't need to buy a science kit: a tray of ice, a couple of eggs and a little flour are enough for a whole afternoon of guessing and testing.

This article suggests three experiments with ice, eggs and flour, suitable for children of roughly 4 to 10. Each one follows the same pattern: your child guesses first, you do it together, look closely, then try to explain.

Before you start: who does what

None of these experiments needs the hob, a knife or any chemicals. A few jobs are still best left to you:

You do: boil an egg in advance (your child doesn't need to be near the cooker), make the warm water for the yeast experiment and check with your hand that it is only warm, and wipe up spills on the floor.
Your child does: the guessing, setting things out, sprinkling salt, stirring, spinning eggs, watching the clock and recording results.
Everyone remembers: nothing used in the experiments gets eaten, and hands are washed after touching raw egg.

Draw up a sheet with three columns: "My guess", "What happened", "Why?". If your child can't write yet, they can draw or tick, and you can write down what they say.

Experiment 1: where does an ice cube melt fastest?

Take five ice cubes of the same size and put each one on its own small plate. Put the plates in different places, then ask: "Which one will melt first?"

Where the ice cube is	My guess (which order)	Fully melted after
On the kitchen worktop
On a sunny windowsill
In the fridge (not the freezer)
On the worktop, with a pinch of salt
In a glass of water

Every ten minutes or so, do a round together. Younger children only need to say whether each cube is "still big", "smaller" or "gone"; older children can note the time.

A few things worth asking about when you look at the results:

The cube in the sun usually melts faster than one in the shade. Why might a sunny spot be warmer?
The cube with salt on usually melts faster than a plain one. In cold places, that is why salt is spread on icy roads.
Where did the water from the ice go? Pour it into the ice tray and put it back in the freezer, and tomorrow there will be new ice cubes.

The string trick: lay a piece of thread across the top of an ice cube, sprinkle a little salt where the thread lies, wait about a minute, then lift the ends of the thread. Often the ice cube comes up with it. The salt melts the surface of the ice a little, then the water freezes again and grips the thread.

Experiment 2: which egg is raw and which is cooked?

Hard-boil one egg in advance and let it cool completely. Put it next to a raw egg of the same size, without telling your child which is which. Ask: "Without cracking them, how could we find out?"

Lay each egg on its side on a flat plate, or on a table with a tea towel, and give it a gentle spin like a spinning top:

The cooked egg usually spins smoothly and for a long time, like a top.
The raw egg turns slowly, wobbles and stops early.
Try this too: while an egg is spinning, touch it with one finger to stop it, then let go straight away. The raw egg often starts turning again by itself; the cooked egg stays still.

How to explain it to a child: the inside of a cooked egg is solid, so the whole egg turns together. The inside of a raw egg is liquid; the shell turns, but the liquid sloshes about inside and slows it down. When you stop the shell, the liquid inside is still swirling, so it pulls the shell round again.

This is a good moment to ask about change: a raw egg can become a cooked egg, but can a cooked egg ever turn back into a raw one?

Experiment 3: yeast, rising dough and a balloon that blows itself up

The yeast used for baking bread is made of tiny living things. Given warm water and a little sugar, they "eat" the sugar and give off bubbles of gas. This experiment lets your child see that gas at work.

Make some warm water and test it on your wrist: it should feel pleasantly warm, not hot.
Your child puts into a small plastic bottle: half a cup of the warm water, a spoonful of sugar and a small sachet of dried yeast. Swirl gently.
Stretch an uninflated balloon over the neck of the bottle.
Guess first: what will happen to the balloon? Then wait, checking every fifteen minutes.

Usually, after half an hour to an hour, the balloon stands up and slowly fills. Set up an identical bottle with cold water, or with no sugar, so your child can compare: which one fills faster? Each bottle differs in just one thing, which is how you find out what makes the difference.

To see real dough rise, mix two small balls of flour and water, one with yeast and one without. Put them side by side, mark their starting size with two pieces of string, and look again after an hour.

Changes you can undo and changes you can't

Together, the three experiments show two kinds of change. Sort them into a table with your child:

Change	Can it be undone?
Ice melts into water	Yes: back in the freezer, it turns to ice again
Raw egg becomes a cooked egg	No
Flour and water become dough	Hard: wet flour never goes back to dry powder
Bread is baked	No

Then challenge each other to find more in the kitchen: melting chocolate, yoghurt, baked biscuits, a sugar cube dissolving in tea. When your child starts asking "can it go back?" on their own, they are thinking like a scientist.

In Dologi, the "Pour and measure" puzzle asks children to pour water between jugs until one holds exactly the right amount, a way of thinking about water and volume that sits very close to measuring in the kitchen.

In short

The kitchen already has what you need for plenty of experiments: ice, eggs, flour, yeast, salt.
Keep the routine of guess, do, look closely, explain, and record it in a simple three-column table.
You handle the boiled egg and the warm water; your child handles guessing, stirring, spinning and recording.
Finish with "can it be undone?" to link the experiments together.