Squash it flat, roll it long, cut it in two, press it back together. Whatever your child does to a lump of modelling clay, it is still the same clay.
That is what makes clay so useful. Your child can change a shape with their own hands, compare it with another one and put it right, and all the while they are learning about shape, size and the parts of a whole.
What you need
- Modelling clay, or salt dough made from two cups of flour, one cup of salt and about one cup of water.
- A board or a tray to work on.
- A plastic knife and a pencil for rolling.
Clay and salt dough are not for eating, so keep the game for children who no longer put things in their mouths.
Copy the model
You make something small. Your child makes the same thing next to it: the same shape and the same size.
| Level | The model | What to compare |
|---|---|---|
| 1 | A ball, a snake, a pancake | Is the shape the same? |
| 2 | A snake as long as the pencil | Is the length the same? |
| 3 | Two parts joined: a snowman, a mushroom | Which part is bigger, and where do they join? |
| 4 | A cube, a cylinder, a cone | How many flat sides does each one have? |
| 5 | A model shown for ten seconds, then covered | Shape and size from memory |
Always check by putting the two side by side. Ask "What is the same? What is different?" before anything gets fixed.
Same clay, different shape
Make two balls and adjust them until your child agrees they are the same size. Now roll one of them into a long snake, and ask: "Is there more clay in the ball, more in the snake, or the same in both?"
Young children often say the snake has more, because it is longer. Don't correct them. Roll the snake back into a ball, put it next to the other and ask again. Nothing was added and nothing was taken away, and children work that out for themselves when they have seen it happen a few times.
Sharing it out
Halves. Roll a snake and cut it in the middle. Lay the pieces side by side. Are they equally long? If not, press them together and try again.
Quarters. Cut each half in half. Then put all four pieces back: four quarters make the whole snake again.
Three fair shares. "Share this lump between three toys so that nobody gets more." This is much harder than halving. Rolling each share into a ball makes them easier to compare.
Twelve little balls. Roll twelve small balls and share them between plates.
| Plates | Balls on each plate | Left over |
|---|---|---|
| 2 | 6 | 0 |
| 3 | 4 | 0 |
| 4 | 3 | 0 |
| 5 | 2 | 2 |
The last row is a good one to talk about. What could be done with the two that are left?
| Rough age | What to try |
|---|---|
| 4–5 | Balls, snakes and pancakes; copying a simple model; cutting a snake in two |
| 6–7 | Models with two or three parts; halves and quarters; sharing twelve balls between two, three and four plates |
| 8–9 | Solid shapes and counting their flat sides; three fair shares; the ball-and-snake question |
| 10 and up | Copying a model from memory; building from a drawing; sharing with some left over and deciding what to do with it |
Ages are only a rough guide, and every child is different.
In Dologi, the Space topic has "Block builder" puzzles, where children choose all the blocks that together make a given shape, with nothing left over. It is the same idea of parts that add up to a whole.
In short
- Clay changes shape without changing amount, so it is ideal for comparing shapes and sizes.
- Copying a model and checking side by side trains careful looking.
- Rolling a ball into a snake and back shows that the amount stays the same.
- Cutting and sharing clay give a first feel for halves, quarters and what is left over.
Read more: Teaching fractions to children: start by sharing a cake