One of the best zoos in Germany
The Erlebnis Zoo Hannover is a wonderful zoo that is expanding all the time. They have devoted a huge area to a children's playground and petting zoo.
The animals are divided according to their habitat, i.e.: the lions are in the Zambesi area and the raptors are altogether in one area. The zoo is proud of their breeding program and often have a huge variety of baby animals: from elephants to wolf pups.
The price during the summer season can be pretty high. If you are staying in Hanover for an extended period of time, I would invest in a yearly pass, which allows you to visit the zoo every day of the year at a considerably reduced rate.
Also, be sure to visit Meyer's Hof, a traditional German restaurant that has some of the best cuisine in the city as far as traditional German food is considered.