International Fund for Animal Welfare and We Are Teachers.
There are actually three curricula to choose from: K - 2, 3 - 5, and 6 - 8. Each curriculum includes an age appropriate video, a student magazine, a teaching guide and excellent lesson plans. All of the work has been done for you. You just have to download it!
Visit my blog, AmyBrownScience.com, for the details and all the links to these outstanding materials.