I know someone who graduated summa cum laude at Harvard. I'm not usually one for ranking people by intellect, but she's not one of the smartest people I know by a long shot.

Meticulous? Sure. Does she present herself as if she's a Harvard grad with the economic status that usually entails? Absolutely. But I know several people who graduated from a small directional university who are absolutely smarter than she is. Same with grads I know from Cornell, Penn, and Yale. Maybe the mystical "school where everyone is actually super-intelligent" exists somewhere, but if so, I don't know the name of it.

Unless your professors are so lazy that they're grading on a bell curve, there's no need to be afraid of any class. Test scores and project grades are based on rote knowledge and level of effort, not innate talent... and Harvard educators are usually vastly superior to those of "lesser" schools.