Back in the 70s many of my college students recorded my lectures. My lecture lab table often had several recorders on it. Students shared the tapes in their study groups. One day I prerecorded a lecture. Walked in the classroom and the students got up and placed and turned on their recorders and I placed my recorder on the table and turned it on play to play my recorded lecture. We all then went over the student center and got something to eat. I later video my lectures and placed them in the library for students to review. Times have changed.
That reminds me of a scene from the movie, "Real Genius," where at the beginning of the semester, there is a class full of people with the professor, later there are some and then more and more recorders, and finally there's a big reel to reel recorder giving the lecture, while every student desk has a tape recorder on it, and not a single person in the class room.
Mark