“Which of you can tell me how we distinguish between the werewolf and the true wolf?” said Snape. Everyone sat in motionless silence; everyone except Hermione, whose hand, as it so often did, had shot straight into the air.
“Anyone?” Snape said, ignoring Hermione. His twisted smile was back. “Are you telling me that Professor Lupin hasn’t even taught you the basic distinction between —”
“We told you,” Said Parvati suddenly, “we haven’t got as far as werewolves yet, we’re still on —”
“Silence!” snarled Snape. “Well, well, well, I never thought I’d meet a third-year class who wouldn’t even recognize a werewolf when they saw one. I shall make a point of informing Professor Dumbledore how very behind you all are. . ..” Rowling, J.K. Harry Potter and the Prisoner of Azkaban (p. 69). Pottermore Publishing. Kindle Edition.

Harry slammed his book shut and called out for Dobby to appear, getting Snape’s wand taken away from him as Dobby popped up, and tossed out the window. “Bad, bad vampy-Snape. You shall not hurt Harry Potter sir!” And with another snap of his fingers, Snape was spread-eagle against the far wall and his mouth sealed shut.

In the meantime, Harry had been busy bottling the memory of the class with Snape from when he arrived up to when he called out for Dobby. Just as he had learned to do from Fortescue while in the alley this last summer. After all, memories were a part of a person’s history, which was part of a family’s history. And Fortescue loved history in all its many forms.

He got Dobby’s attention and had him take the memory along with a copy of all the school teaching memories from his vault, to “the head of the Gringotts Hogwarts monetary fund, and another copy to the WEA with a word to each that I want a refund on my family payments to the school for Defense, History, Potions, Divinations, and Care since I’ve been taking them here. And an investigation into the actual teaching practices the parents are paying for.
“Also, if I am, by law, being forced to be here, then, for the mandatory classes that I am reporting about, I want the refunded money to go to IWEA approved tutors to teach me at those time periods.”

He packed up his books after Dobby popped off and glared at the now pale potions professor. “It might interest you to remember, MR. Snape, that until this year, we’ve had piss poor instructors in this class. And that is why we are behind.
“NOT that any of you did anything about it then of course.”
And walked out.