A bright story that demonstrates the ways we use math in everyday life. César wants to borrow one of his little sister’s crayons, but she won’t let him touch them. Only Gabi can give him the crayon he wants, if only she can figure out what cerulean is. Thus ensues a clever process of elimination, with territorial Gabi facing off against the increasingly frustrated ­César. It’s a window into an all-too-familiar sibling ­dynamic, a slice of life many readers can identify with. Along with the subtle math hints, both Gabi and César sprinkle in Spanish words. Further explanation can be found in an author’s note, along with interactive tips for adults, showing how to encourage the math connections during reading. VERDICT A cozy sibling-oriented spotlight on daily math usage.
—School Library Journal