People talk about intelligence a lot, but the sheer difference in interest is just as big, if not a bigger factor.

In an average class, you get most kids - who are mostly content to be there. And then you get the outliers. There's that one kid who appears to be suffering something just short of physical pain whenever he's in class learning something. Then there's the kid who has already read all his textbooks in the first week, for fun, and even retained a lot of it, because he was engaged with the material.

They may have the same exact intelligence, but the outcomes could not be more different.