<em>Pathos</em> is a term first introduced by Aristotle, who is often referred to as the father of rhetoric. It's also called the appeal to emotion and refers to using arguments to draw out certain emotions in the audience and through them get them to change their point of view.
If you wanted to convince your teacher to change your grade using pathos, you would have to tell a story that would make them feel compassion. For example, you could tell that you were ill and didn't feel well enough to study, ask them for another chance, and similar.
