http://www.discoveryeducation.com/teachers/  (Grades K-12)

http://www.loc.gov/teachers/  (Classroom Materials/Professional Development)

https://www.teachingchannel.org/ (Watch, share, and learn new techniques)

http://www.pbslearningmedia.org/ (Learning material from Pre-K - Grade 13+)

http://www.parcconline.org/for-educators (New Assessments)

http://www.scholastic.com/teachers/teaching-resources (General Teaching Resources)