There aren't a lot of Spanish children's books out there that deal with family names (padre, madre, abuelo, hermana, prima, etc.), but Yo Tenía Un Hipopótamo does an excellent job of introducing the basic family relationships.
The book opens up with a young boy eating animal crackers, but the crackers in his mind become real. He then decides to give away various animals to different family members and friends.
The illustrations are colorful and humorous. The language is simple and repetitive enough for beginning students to understand the gist of the story. It is also a great book for those students just learning to read!
Using Yo Tenía Un Hipopótamo you can talk about family members, animals, and practice the construction "Se lo (la) di" (I gave it to him/her).