Those of us who grew up coloring remember the cardinal rule: stay inside the lines. But those who pick up the Patterns of the Universe coloring book have to stay in the sines (and cosines and tangents ...

Counting, coloring, and collective nouns go hand in hand in a coloring book that features striking linoleum prints of 12 flying animals, including butterflies, flamingoes, bats, and sugar gliders.

Crayons, of course. Scented markers. Colored pencils, presharpened. And coloring books by the jillions. Why do people like coloring so much? For grown-ups, I can totally get the nostalgia — and the ...