>>10950877I would say any class where you're asked to do formal proves.
Any brainlet can learn to find the area under "well behaved" curve. But if you up it a few notches, by asking: Prove that the Area under the curve f '(x) on the interval [a,b] is equal to the difference f(b) - f(a), that's a slightly different story.
A student with less than 120 will have difficulty answering that question.
Another question would be alike to ask why does a negative times a negative number return a positive value? Someone with more than 115 shouldn't have a hard time answering that one.
