https://www.edx.org/
Their gimmick being:
Those institutions include outfits like Harvard, Princeton, and Berkeley.Access 2500+ Online Courses from 140 Institutions. Start Today!
Many (all that I have yet looked at) are free to watch/listen, you only get charged for a "verified certificate".
So if you just wanna educate yourself, rather than acquiring marketable skills specifically to market them, this is withing pissing distance of hte mother lode. Many courses involve quizzes, to check you paid attention during the lecture. The course on vaulted structures I've got running right now, it comes with bloody calculus exercises.
I used to love, passionately, iTuners U. Which was where educational materials had been collected on iTunes. But they cancelled that a few years ago, and finding a a lecture on an arcane subject, presented by qualified academician, involved digging through hundreds of podcasts, and whatever I found would not be curated, obviously.
So this makes me very happy, and I hope you happy by it, too!