Early one morning at the Denver Zoo, a polar bear gives birth to two tiny babies, then abandons them. The zoo staff must raise the babies, but there are many things they don't know. What foods are best? How much should the cubs eat? Once they figure out the answers, the cubs quickly become healthy, happy young bears. Young readers follow Klondike and Snow as they grow from fragile newborns to large, lively bears, and along the way they'll learn about fractions.