Because you can get stuff from lectures without paying full attention. I download those Open Yale Courses lectures, and listen to them while driving to work. Dr

Because you can get stuff from lectures without paying full attention. I download those Open Yale Courses lectures, and listen to them while driving to work. Driving, obviously, takes up some fraction of my brain, but I find that I still have plenty left over for listening. Would I get more out of it if I listened while sitting at a desk and taking notes? Probably. But I'm getting a lot more than nothing out of it. And obviously TV-watching is harder to combine with lecturing (among other things, the student presumably had to have closed-captioning on), but fundamentally the idea of doing two things at once when neither of them demands your complete attention isn't that weird.