By Pat Hutchins
Ma makes a dozen cookies for two children, and then the doorbell keeps ringing.
Ma sets a plate of twelve cookies on the table, and Victoria and Sam work out that's six each. Then the doorbell rings and two friends come in, so now it's three each. The doorbell rings again. And again. Every time, more children crowd around the same plate and everybody's share gets smaller, until there are twelve children and exactly one cookie apiece and nobody dares take a bite. Then the doorbell rings one more time, and it's Grandma, with an enormous tray.
The text is short, repetitive, and almost entirely dialogue, so a child who is only just reading can carry a lot of it themselves. The real trick is that the suspense and the math are the same thing. Every ring of the doorbell is a joke and a division problem at once, and your child feels the shares shrinking in their stomach before anyone says a number. It's funny, it's a story, and the arithmetic is load-bearing rather than bolted on.