OpenLearn (Open University)
OpenLearn is The Open University's free learning platform, and it draws on the same teaching material the OU uses in its degrees, reworked into self-contained study units. You will find hundreds of free courses and thousands of shorter articles and activities across science, technology, health, mathematics, history, the arts, business, and languages, each tagged with an academic level from introductory to advanced. As a body of openly usable, carefully written educational content produced in the UK, it is one of the strongest around.
There is no bulk dataset and no API, so in practice you crawl the HTML pages under open.edu/openlearn and extract the main teaching text. Many units also publish downloadable versions (PDF, ePub, and sometimes Word) that are cleaner to parse than the surrounding page furniture. When you chunk for retrieval, lean on each unit's own section headings: OpenLearn material is written in tidy, well-signposted sections, which makes it unusually easy to split into sensible passages.
It suits a UK-flavoured tutoring or revision assistant, a bot that explains a concept at a chosen level, or any education-focused RAG system that benefits from pedagogically ordered material rather than raw web text.
The licence is the thing to watch, and all three parts of it bite. OpenLearn is CC BY-NC-SA 4.0: the NonCommercial term rules it out of any commercial product, a common and easily missed trap in educational data; ShareAlike means anything you redistribute must carry the same licence; and attribution to The Open University is required. Some units also embed third-party images or clips under separate terms, so do not assume a whole page shares its unit's licence.
It sits alongside MIT OpenCourseWare and LibreTexts, which carry their own NonCommercial or ShareAlike catches, so if you need commercially usable teaching content you may have to fall back on public-domain or CC BY sources.
Related sources
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Khan Academy
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