Description Playful otters are some of the most high-interest animals in the zoo and in the wild. Finding out about otters while also learning about odd and even numbers makes math seem like play. The concept of odd and even is an important one in the elementary math curriculum. Readers will be motivated to count the otters in the colorful photographs and figure out if the sums are odd or even. Math questions are paired with an answer key for easy self-assessment..