General:
CK-12( https://www.ck12.org/teacher/)
Crash Course Kids( https://www.youtube.com/user/crashcoursekids )
EdPuzzle (https://edpuzzle.com/)
Khan Academy / https://www.khanacademy.org/
NearPod( https://nearpod.com/ )
PearDeck(https://www.peardeck.com/ )
PBS Learning Media https://mass.pbslearningmedia.org/
Social Studies/History:
Extra History( https://www.youtube.com/extracredits/featured )
ICivics( https://www.icivics.org/ )
PBS Learning Media-Civics and Government ( https://mass.pbslearningmedia.org/subjects/social-studies/civics-and-government/ )
Inquiry Design Model(Social Studies) (http://c3teachers.org/inquiries/ )
Youth Stand Up(PBS): https://mass.pbslearningmedia.org/collection/youth-stand-up/
Science and Engineering:
pHET(https://phet.colorado.edu/en/simulations/ )- Science and engineering simulations
PBS Design Squad ( https://pbskids.org/designsquad/video/ )-Engineering Design Challenges for K-12
Teach Engineering ( https://www.teachengineering.org )
Youtube.com (http://www.youtube.com )