"Before we begin today's lesson," said Snape, sweeping over to his desk and staring around at them all, "I think it appropriate to remind you that next June you will be sitting an important examination, during which you will prove how much you have learned about the composition and use of magical potions. Moronic though some of this class undoubtedly are, I expect you to scrape an "Acceptable" in your OWL, or suffer my ... displeasure."