@mathmom, It is not the core curricula that is particularly hard. It is sometimes that a lopsided student, while being excellent on a certain subject (say, science), is relatively weak compared to his/her peers in a humanity, writing/discussion intensive class. Such a student may even have been a relatively OK student at his/her non-magnet public college. I actually know a case where a student who was a valedictorian at his non-magnet public high school was struggling in almost all humanity classes. There is little hope he could remedy the situation when the peer students are much better than him on some required core courses. One student could write a paper in one evening and get a relatively good grade, while he could spend 2 weeks on this paper and was still at the bottom of the class. It is very difficult for him to catch up. If such a student attends a college that accepts AP credits for core education credits, he does not need to take any of these core education classes (i.e., he could use his AP credits.)
It is not the class that is hard. It is the peer students in the same class that makes a class for such a loopsided student. (I think a CC oldtimer, BlueDevilMike once made the same point. He even said that at his college, Honor Physics is “easier” than the General Physics, if I remember it correctly. Unlike the upperclass or grad school level classes, the “difficulty”
level of such introductory level classes has nothing to do with the depth of the materials covered in the class. It has everything to do with the achievement levels of peer students in comparison because of the grading curve. A student from a lower performing high school tends to not have a “fighting chance” due to their poor preparation in his/her secondary education. I actually think it is kind of cruel to put such students in the same class room with the students who are much more prepared in academics.)