Cook with one scoop. Pick a simple recipe and hide every measuring cup but one, say the quarter cup. Turn each amount into a number of scoops before you start. If an amount will not come out as a whole number of scoops, try doubling or tripling the recipe until it does.

Before chapter 3. Can you make a third of a cup out of quarter-cup scoops?

The answer. No. One scoop is a quarter (0.25), which is short of a third (about 0.333), and two scoops are a half, which is too much. A third is one and a third scoops. In the book Halver triples the recipe: three thirds make one cup, which is four scoops. The flour becomes nine scoops and the sugar six.

The recipe: lemon cake (makes three small cakes). 9 quarter-cup scoops of self-raising flour, 6 scoops of sugar, 4 scoops of milk, 3 eggs, the zest and juice of 2 lemons, and half a cup of melted butter. Mix, divide between three small tins, and bake at 180°C (gas 4) for about 25 minutes. A grown-up handles the oven.

The grown-up layer. Changing the whole so a part fits is the idea behind common denominators. FractionForge has the tools.

For the ride home. Ask: with only a half-cup scoop, which amounts can you make?