Destrey strode into the Defence classroom, expecting her Seventh years were already assembled. If not, they would just miss out in today's lesson. By now, they ought to know better.
"Most of you," she began, "are going to sit the Auror exams."
"Or you'll go on to become hitwizards, or work in some other part of the Ministry. If you remember nothing else from this subject, you should remember this lesson, so listen up."
Without looking, she flicked her wand sharply at the board.
Case Study
"Imagine you're at work, doing whatever you plan to do after you graduate. You've just been told about two experimental new spells for defensive use in your department."
"You're told the that when protecting a group of six hundred people, the first spell might save two hundred of them."
Spell 1 = 200 of 600 ppl saved
"And you're told that the second spell has a thirty-three percent chance of everyone, but a sixty-six percent chance of saving nobody."
Spell 2 = 33% chance of saving all 600, 66% chance of saving 0
"Which spell are you going to choose, and why?"
"Feel free to discuss it with one-another."