Ask HN: Best MOOCs You've Taken?

MOOC = Massive open online course? https://en.m.wikipedia.org/wiki/Massive_open_online_course

I presume?

EDX 6.002x Circuits and Electronics, which is not longer available in that form was alright.

For me, I knew a lot of the electronics so it turn out to be mainly a refresher in doing algebra.