This classic rhyming book exposes preschoolers to a new kind of pattern—not a repeating pattern, but a growing pattern. With each creature that joins the pile of sleepers, the story illustrates a plus-one growing pattern. This is an easy pattern for young children to recognize and extend because it’s the structure of our number system (1, 2, 3, 4, . . .) and often looks like a set of stairs. Growing patterns increase or decrease by a constant amount. Recognizing patterns like this lays the foundation for algebraic thinking.