Actually in the CalTech class I mentioned, the professor got to know some students’ work. He got to know mine, for example. He monitored and participated in the online forum, where some students, including me, shared information and asked questions. When I emailed him later about another issue, he remembered me from my postings and complimented me. Or maybe he looked up my postings, but I think he probably remembered me, because there were so few women and IIRC I posted under my own name.
I of course didn’t pay CalTech tuition for the course; I paid nothing.