Imagine a water bottle with its cap screwed on tight. You could put it under a waterfall, and not one drop would get inside, right?
The "mocker" (that person who makes a joke out of everything, thinks they know more than the teacher, doesn't take anything seriously) is just like that capped bottle. He could go to the best school, but he learns nothing because the "cap" of pride is closed. But whoever has discernment (whoever is humble and pays attention) is an open bottle. The water of knowledge flows in easily, easily, and fills up fast!