OpenLearn (Open University)
OpenLearn is The Open University's free learning platform, offering courses and educational resources across a wide range of subjects and academic levels. It draws on Open University course material, making it a strong UK-based option for education content.
Content is released under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 licence. You can reuse and adapt it for non-commercial purposes as long as you credit The Open University and license your derivatives under the same terms. The NonCommercial clause rules it out for commercial products.
Related sources
LibreTexts
One of the largest open textbook platforms, covering higher education with some K-12 material. Hosts interlinked textbooks and reference material across science, mathematics, humanities, and social sciences. Mostly NonCommercial, so commercial use is ruled out.
Mason OER Metafinder
A discovery tool that runs a real-time simultaneous search across 21 different sources of open educational materials, rather than searching a static database. Useful for finding content to ingest, not a dataset in itself.
MERLOT
A curated collection of online learning and support materials, plus content-creation tools, led by an international community of educators, learners, and researchers. Points to resources hosted elsewhere across many disciplines.
MIT OpenCourseWare
Teaching materials from more than 2,500 MIT undergraduate and graduate courses, published freely online. Includes lecture notes, assignments, and exams. Released under a NonCommercial licence, so it is free to use for non-commercial purposes only.