BBC Learning - while the BBC’s education pages are no longer updated, there's much useful content here, from language learning to BBC Bitesize for revision. No TV licence required except for content on BBC iPlayer.
Coursera – collaborating with 190 world-leading universities, Coursera allows anyone to build skills with online courses and degrees. Coursera offers more than 2,700 courses, 250+ specializations, and more than four accredited degree programs, all generally free. Particularly good for computing.
Crash Course - offers fun and informative educational videos on a range of subjects.
FutureLearn - offers free to access 100s of courses. Users only need to pay to upgrade if they need a certificate (own account from age 14+ but younger learners can use a parent account).
Ivy League MOOCS - most of the eight Ivy League universities are now offering some form of publicly available free online classes. MOOCs (massively open online classes) offer learners everywhere the opportunity to learn from Ivy League instructors and interact with other students while completing their coursework.
Seneca - join 2,750,000 students using Seneca to learn at KS2, KS3, GCSE and A-level. Tons of free revision content, with paid access to higher level material.
TED Ed - TED's youth and education initiative aims to spark and celebrate the ideas and knowledge-sharing of teachers and students around the world, offering a range of thought-provoking videos.