Children are introduced to the concepts of sorting and classifying in this bedtime story.It is getting close to bedtime, and Marco's mother asks him to put his toys away. Marco-who thinks of himself as a scientist-corrects her: "You mean time to sort the animals." And that's what he proceeds to do. Marco sorts his animals into three baskets labeled "Flying Animals," "Swimming Animals," and "Animals That Move on Land," but the animals will not sleep. So he sorts them by color: "Mostly Brown," "Black and White," and "Colors of the Rainbow," but Zebra is upset to be separated from Giraffe. Next, Marco sorts his animals by size: "Small," "Medium," and "Large," but the big animals are cramped and the small ones feel cold. Finally, Marco ranges them around his bed from biggest to smallest, thus providing them with space to move and helping them to feel safe. Everyone satisfied, they all go to sleep. While the plot is flimsy, the general idea that organizing and classifying can be accomplished in many different ways is clear. Young children are also presented with the concept that different classifications can lead to different results. The illustrations, while static, keep the focus clearly on the sorting taking place. Marco and his mother have brown skin. The backmatter includes an explanation of sorting in science and ideas for further activities.Nothing riveting but serviceable enough. (Math picture book. 3-5)