By far the easiest course I've so far completed on EdX is From Goddard to Apollo: The History of Rockets Part 1. That's not to say it wasn't enjoyable or that I haven't taken anything away from it, but comparing it to another introductory course like CS50 is like comparing apples to oranges. I guess that's not really the courses fault though and it was pretty interesting learning about the origins of rockets, it's just that it never felt to me as though it was really pushing you. You do have to write some assignments, so it's not all just watching videos, but I'm not even sure the assignments get checked by another person. Once you've submitted the text, you're asked if you've completed all the required points; I'm not sure if I could've just submitted a picture of a cat and it would've accepted it or not, but some sort of feedback might have been good. Still, if it helps stop the brain from rotting any further then thats good.