The Bronx Zoo has a good page of resources for elementary school and middle school educators. Among the resources available on the Bronx Zoo’s educators page are videos (served via YouTube), lesson plans, and interactive online activities. The lesson plans are generally oriented toward an audience that is planning a zoo visit, but some of the plans can be used without making a zoo visit. There are four interactive online activities designed for elementary school and middle school audiences. The interactive activities include two identification games, a quiz, and a narrated slideshow about camels adapting to their environments.

Applications for Education
While most of the lesson plans on the Bronx Zoo website are intended for those who will be visiting the zoo, the lessons could be adapted to suit other zoos. Likewise some of the lessons could be used without visiting a zoo at all.

Here are some related items that may be of interest to you:
Fun Dinosaur Games and Lesson Plans
Teacher Linx- Create and Share Lesson Plans
Science Netlinks – Dozens of Science Lessons