I don't think he is active teaching now. He holds emeritus now so he has no duty to teach unless he wants. He probably spends most his time working on AdaCore a

I don't think he is active teaching now. He holds emeritus now so he has no duty to teach unless he wants. He probably spends most his time working on AdaCore and its spinoff. I suspect his attitudes is due to his father's influence, who was a very famous organic chemistry researcher Michael J. S. Dewar. In fact you can learn the similar experience just by doing a project yourself. I learned most stuffs in my life from projects. A course just gives a pressure to finish something before deadline. PG and YC are using the demo day to push applicants to finish something and with a potential payoff for finishing it. (Why? because of human nature tends to procrastinate!) So maybe you just pick a non-trivial but not too difficult problem (Unless you aim for Turing Award and wants to be the first one to prove/disprove P = NP), find some friends/comrades who wants a challenge. Set up a deadline and payoff and go for it. You learn by doing it and the more you do it, the easier it will be.