To be honest, I pretty much lost interest in OOP. I found the ML/Racket parts of the course much more interesting (and less confusing) - even though I barely knew any FP and had actually studied some OOP. Perhaps I was biased, either against OOP or Ruby, which was used to teach it. Hmm...

Even though I found the Ruby/OOP part of the course less interesting than the ML/Scheme parts, I feel like it gave me a much better understanding of OOP.

Actually the optional piece where he went through a derivation of OOP at the end of the Scheme portion was also one of the most helpful things for me.