Science

CK-12: CK12 offers free videos organized around the Next Generation Science Standards.  It's geared mostly towards middle school and high school, but it doesn't hurt to browse as an elementary teacher as well.  A bunch of great resources for teachers, or to pass on to parents and students!

Monterey Bay Aquarium Animal Cams:  Watch the jelly fish, sea otters, penguins and more through a live feed.

San Diego Zoo Panda Cam: Watch the pandas!

National Geographic for Kids Videos: Check out videos on animals, weather, cool places, interesting people, and much more.  A great resource!

National Geographic for Kids Magazine Back Editions:  Search all the back editions of NG for Kids for Young Explorer, Pioneer, and Pathfinder editions.  Most are about animals, but if you have time to glance through few you'll find a bunch of great non-fiction reading!

Dichotomous Key Jelly Bean (Classification Key PDF): The key that I love to use when teaching about classifying.

NASA For Educators: If you're looking for up to date space information, this is the place to be.  Then send your students over to the NASA Kids Club because it's super fun!

Discovery Kids: The kid friendly Discovery website.