Ellen Greenberger and her colleagues recently researched what she termed an "increased entitlement" among college students. The study involved multiple content areas, and is not specific to mathematics....though echos of such come through loundly.
Basically, a divide has occurred. Teachers equate coming to class and meeting standards as a earning a default grade of a C, while students view the default grade as being an A. In Greenberger's study, 33% of the students expected B's "just" for attending lectures, and 40% expected B's for completing the required reading. How does either of these demonstrate any gained understanding?
Consider this claim by a college senior: "I think putting in a lot of effort should merit a high grade. What else is there really than the effort that you put in? If you put in all the effort you have and you get a C, what is the point? If someone goes to every class and reads every chapter in the book and does everything the teacher asks of them and more, then they should be getting an A like their effort deserves. If your maximum effort can only be average in a teacher's mind, then something is wrong."
As to why this perceived sense of entitlement has occurred, Greenberger listed factors such as increased parental presure, competition among peers and family members, and a heightened sense of achievement anxiety.
Noting that this phenomena of entitlement is not new, I suggest that Greenberger has missed several other "causational" factors, ranging from the protective approach of state/national educational policies to documented erosion of grading standards to the coddling and building of false sense of achievement abilities by some teachers in both K-12 schools and colleges/unioversities.
Source: M. Roosevelt's "Student Expectations See as Causing Grade Disputes," New York Times, 2/18/2009