I teach at Leiden University College, which prides itself on its small-class, interactive-teaching environment (we just won a teaching award of sorts). This environment is not just based on head count and physical space, but also rules and norms such as mandatory attendance and a ban on laptops/mobile phones, respectively.
Just the other day, we were having a discussion of which institutions students might want to change at LUC and one student said "I hate mandatory attendance. After all, if I miss the class, then I am the one who suffers, right? Shouldn't I have that choice?"
This logic is pretty sound when it comes to the student's personal experience (a private good), but it entirely misses the point of LUC's model, i.e., a seminar discussion that involves all students in listening and speaking, with the professor introducing new topics and encouraging others to bring their own thoughts, beliefs and experiences into the discussion. (This may sound like a liberal arts caricature, but it's the goal that I and many of my colleagues have, even if we don't always achieve Hollywood levels of humor, sudden genius and random discovery!)
The student, in other words, had failed to appreciate the importance of their attendance on the experience of others -- a failure that's particularly ironic in the particular context of the current course ("Foundations of common-pool resources management"), which is all about understanding, protecting and building shared spaces -- including learning spaces.
As part of that discussion, I mentioned just how difficult it is to teach students who are neither attending nor following the material, using my experience teaching at Simon Fraser University in Vancouver (SFU).
In early 2013, I taught two courses at SFU: a seminar for 15 students and a lecture for 90 students. In both courses, about 80 percent of my students were from mainland China, where plagiarism is tolerated and paper credentials are more important than learning.
But I saw a difference in attendance, participation and learning. In my smaller class, we had interesting, wide-ranging discussions. In my larger class, half the students only attended for exams. On most days, there were usually 40 or so ill-prepared students -- a situation (and norm) that frustrated me, especially as I had had a much better experience teaching the same number of students at UC Berkeley, where attendance and engagement was consistently high.
What does frustration look like? Well, one day I just stopped teaching and cancelled class because I couldn't find a single student who had done that day's reading. Since I was recording all my lectures,* you can watch my meltdown (the video starts at 14:30):
Bottom Line: It's hard to learn if you're not there, just as it's hard to teach if students are not prepared, but most of all it's hard to learn if students are not exchanging ideas, critiques and insights with each other. The professor is there to help learning, not to drop knowledge in your ear. If you're looking for that kind of "school," then watch Khan Academy videos, as they are cheaper and usually better than most "broadcast" lectures.
* I also recorded my Berkeley lectures, which have 20x the views as my Simon Fraser lectures, so watch those if you're interested in Environmental Economics and Policy.