The National Geographic Society, a nonprofit scientific and educational organization dedicated to exploring our planet, protecting wildlife and habitats, and helping assure that students in K-12 are geographically literate, offers teaching resources, units, lessons, activities, guides, and educational games for K-12 teachers.
Resources are grouped K-2, 3-5, 6-8, and 9-12 and can be filtered to streamline searches.
On YouTube (Young Learners)
On Twitter: https://twitter.com/NatGeoEducation
On Facebook: https://www.facebook.com/natgeoeducationOn Google+: https://plus.google.com/+NatGeoEdOrg/about