While the teacher was walking students through how to do loops, I got permission to hack away in the back of the room on this. I ended up building a BASIC-like interpreter with a decent graphics API. By the end of the class, my project was a multi-level breakout game I'd written in the interpreter I'd written. TLDR; two years later, I talked to a girl.
That same game project I started then still has been going on since then, multiple compilers and VMs written to do parts of the game. It's ended up an incredibly complex monstrosity with procedurally generated worlds and randomly altered scripts (some actions just won't be available on some play-throughs).
I spent probably 30 minutes 2 or 3 times a week for a couple of months. Most of that was probably adding features to my interpreter and coding the game itself. I recall it being extremely clear to me, even without any sort of formal CS. Even things like working with the stack and recursion were clear to me at the time.