The meatrix

If you're teaching about the dangers of factory farming, this animation should amuse your students, especially those fans of "The Matrix"

http://www.themeatrix.com/

If you're teaching about organic farming view this five minute mini-movie which tells the tale of a small band of organic vegetable puppets -- Cuke Skywalker, Ham Solo and Chewbroccoli
http://www.storewars.org/flash/