I go to a fairly prestigious engineering school and it works the opposite way here. Math and science grades are always curved. You have no idea what grade you are going to get for the class until you get it. The grades you receive are more often than not more than you've earned. Either, the grading scale is lowered (90 and up is an A, 86-90 is A-, etc.) or your grade is boosted at the end. For example, I got a B in an organic chemistry class when it should have been a C-.

On the other hand, every humanities class I've taken, I've gotten the exact grade I have earned.