We’re supposed to practice the Cruciatus Curse on people…

““We’re supposed to practice the Cruciatus Curse on people who’ve earned detentions--” “ What? ” Harry, Ron, and Hermione’s untied voices echoed up and down the passage. “Yeah,” said Neville. “That’s how I got this one,” he pointed at a particularly deep dash in his cheek, “I refused to do it. Some people are into it, though; Crabbe and Goyle love it. First time they’ve ever been top in anything, I expect. “Alecto, Amycus’s sister, teaches Muggle Studies, which is compulsory for everyone. We’ve all got to listen to her explain how Muggles are like animals, stupid and dirty, and how they drove wizards into hiding by being vicious toward them, and how the natural order is being reestablished. I got this one,” he indicated another slash to his face, “for asking her how much Muggle blood she and her brother have got.” “Blimey, Neville,” said Ron, “there’s a time and a place for getting a smart mouth.” “You didn’t hear her,” said Neville. “You wouldn’t have stood it either. The thing is, it helps when people stand up to them, it gives everyone hope. I used to notice that when you did it, Harry.” “But they’ve used you as a knife sharpener,” said Ron, wincing slightly as they passed a lamp and Neville’s injuries were thrown into even greater relief. Neville shrugged. “Doesn’t matter. They don’t want to spill too much pure blood, so they’ll torture us a bit if we’re mouthy but they won’t actually kill us.” Harry did not know what was worse, the things that Neville was saying or the matter-of-fact tone in which he said them.””

— J.K. Rowling