Some colleges don't appear to care (seriously). They are looking for tuition $$ - and to meet enrollment goals; flunking students is not a good way to do that - tying professor rankings to student evaluations, which are to a large degree tied to grades, however, helps make sure the professors aren't chasing off the clients.
That can be challenging, frankly - but to a large degree, in college, the onus of learning ought to be on the student; there is a reason professors have NEVER taken classes on HOW to teach - the ADULTS they are dealing with ought to do the reading, be able to pay attention to the lecture, STUDY - and learn the subject matter. That was understood when I was in school - however, now, to a large degree the students EXPECT much more; powerpoint presentations, lively lectures - hands on this and that; basically it is the professor's job to KEEP them interested. Also, they expect the lecture to be posted on line, and often lecture notes as well. They expect study guides prior to tests. If a professor knows their , and does all of that, I am comfortable in hanging poor performance on the students.
What we have begun to recognize is the system is become seriously broken. When the lackadaisical professors teach the pre-req classes, give lots of "A's" and pass the kids along; they get seriosly bitter when they stumble into my wife's Biochem 301 class, having been passed through high school, then through the first couple of years of college, and are met with a class that is merciless. This class begins to tie ALL of your Chemistry, Biology and Calculus together in one big intellectual orgy (yes my children are all smarter than me) - and these (up to this point happy go lucky 3.8 average) students get flattened. This one seperates those that have a shot at med/grad school from those that don't; it should happen sooner, IMO - by then kids are Juniors, and think they are O.K; only to learn they aren't so much.
