<p>In science classes the situation is particularly hard to quantify. My d is taking a large lecture that meets twice a week with full professors. She has found them happy to entertain questions, etc., outside of class. The labs are led by grad TAs (which makes perfect sense to me in an intro lab course; more advanced students regularly work in the lab with professors) who are also very available in person and via email outside of class. There are regular review sessions led by a Ph.D/M.D. whom the students adore. In some science classes there are also paid undergrad TAs who are available in the dining halls to offer ongoing support. Ironically, as the ratio of non-profs to profs gets “worse,” the students are actually getting more support. When I was in college, going to a lecture course was a little like going to a movie. You showed up, listened, and left afterward. Today the lecture classes offer far more to students.</p>