The story in three lines. Kerf cuts a square of cloth into nine patches, Miro and Moro lay them in rows, and Dreamer sews the corners and edges but forgets the middle. Tí holds up the quilt with a hole in it. Tila counts, and Tí finds the missing patch and sews it in with Bà Tư.

The five nights. Night one, just listen. Night two, pause before the bold words. Night three, join in the four refrains. Night four, stop at the hole and ask "what's missing?" Night five, let your child tell it to a toy.

One thing to do at the table. Fold a square of paper in three one way and in three the other, then cut along the folds (a grown-up helps with the scissors). Nine squares. Lay them in rows, take one from the middle, and see who notices.

The grown-up layer. A whole is all of its parts: the idea under fractions, area and, much later, (a + b)². Dreamer makes this mistake again at eight in ArrayPals and at twelve in IdentityForge, so a child who finds the missing middle now is meeting an old friend later. PatchPals plays with the patches.