US Dept of Education Office of Educational Technology
https://tech.ed.gov/open/
University of Pittsburgh LibGuide
Yale Poorvu Center for Teaching and Learning
University of South Carolina LibGuide
These are just a few of the many resource pages available on a Google search.
BetterLesson
"We, at CK-12, believe that every child on this planet should have equal access to a great education".
Curriki
"Members from every country around the world are coming together on this platform to share, collaborate, and connect in order to make the best teaching and learning materials universally accessible and useful".
Gooru
"A full spectrum of educational resources, activities, and assessments are right at your fingertips. Our online platform was designed so that you can have access to the best available teacher-curated and research-based course materials to personalize for your students and develop into your own curriculum."
My Digital Chalkboard
The Digital Chalkboard is where California educators get connected, collaborate, and share the best practices, best resources, best strategies — you might say the best of the best.
https://www.mydigitalchalkboard.org/
The National Science Digital Library
A collection within OER Commons database
https://nsdl.oercommons.org
OER Commons
"OER Commons is a public digital library of Open Educational Resources. Explore, create, and collaborate with educators around the world to improve curriculum".
Open Course Library
"A collection of high quality, free-to-use courses that you can download and use for teaching". Developed by the State of Washington.
http://opencourselibrary.org/
OpenEd
"Standards aligned K-12 resources, tailored for each student based on assessment results".
https://www.opened.com
OpenStax
Open Stax at Rice University. "Peer Reviewed. Openly Licensed. 100% Free"
https://openstax.org/subjects
Open Up
"Our non-profit's mission: to increase equity in education by making excellent curricula freely available to districts".
http://openupresources.org/
Share My Lesson
"Share My Lesson is a destination for educators who dedicate their time and professional expertise to provide the best education for students everywhere. Share My Lesson members contribute content, share ideas, get educated on the topics that matter, online, 24/7."
https://sharemylesson.com/
UnboundEd
"We provide free, standards-aligned resources and immersive training for teachers and leaders in pursuit of equity."
https://www.unbounded.org/
Resources that are openly licensed benefit schools in a number of ways, but most notably they help to:
US Dept of Education Office of Educational Technology
https://tech.ed.gov/open/