A color-by-number page is thirty-six addition facts wearing a disguise. Each square holds a sum, the key says which crayon each answer takes, and the picture only comes out if the arithmetic does — which is a kind of checking no answer key can give.
The answer key prints on a separate page.
The four numbers in the key are spread apart on purpose, so a child who miscounts by one gets a clearly wrong color rather than a neighboring one that looks almost right. Every square is a one-step fact, and the same answer is asked with different pairs — the sky of a picture is fifteen squares, and printing the same sum in all fifteen would be one question asked once.
Sums stay within ten or within twenty. The twenty sheets include pairs that cross ten, which is the year's real work and the place where counting on fingers runs out.
