By Theoni Pappas
A cat falls asleep on a mathematician's desk, wakes up inside whatever she was working on, and pulls your child in after him.
Penrose was Theoni Pappas's real cat, and he really did sleep on her papers while she wrote. In the book he keeps waking up somewhere he doesn't belong. He dozes off on a page of numbers and finds himself among the primes, who are standoffish and won't let anything divide them. He meets a Mobius strip and walks the whole way around it without once crossing an edge. He runs into a tribar that can't exist, a rectangle convinced it's the most beautiful shape in the world, a fern built out of smaller ferns forever, and a number so big it has a silly name. Each visit runs two to four pages, told as its own little story, with Pappas's own diagrams beside it. There's no plot tying the book together and no order to hold to. Penrose wakes, wonders, and goes back to sleep.
This is the book for the child who has decided math is adding and subtracting, finds it boring, and isn't wrong about the version they've been handed. None of it looks like a worksheet. Pappas taught the subject for close to twenty years and she plainly loves its strange corners, so what your child gets is one person being genuinely excited, two pages at a time, about things that are odd and true. Know what you're handing over, though: it's a math book wearing a cat suit. Penrose has almost no personality, nothing happens to him, and his whole job is to be curious so the diagrams have someone to talk to. A child who wants an actual story about a cat may feel misled by chapter two. A child who wants the ideas won't notice. The chapters stand alone and run two to four pages each, so you can open anywhere and spoil nothing, and an eight-year-old and a twelve-year-old can both come away with something from the same page.