The part inside oneself that knows, and will answer, all the questions the teacher asks during any given class.
Particularly bad when present in a science/mathematics lesson.
Taken from the character Hermione Granger an annoying know-it-all from the Harry Potter series of books & films.
Girl 1: Man, I felt like such a total bitch in chemistry today.
Girl 2: Why's that?
Girl 1: I couldn't keep my Inner Hermione under control, and spent the whole feakin' class with my hand in the air.