Harry opened his mouth, but couldn't find the words, at first. Then he closed his eyes for a moment, opened them again, and said, "Well, one of the most important things in a duel of any kind is keeping calm, as much as you can. If you're not calm, you won't be able to remember anything. So, we're going to start with something pretty basic, Expelliarmus. After you all learn it, everyone's going to split up and use it against each other, while the Room hopefully provides extremely loud music which could be a distraction." Sure, that would work. A couple of groans ensued at mentioning Expelliarmus, since it was such a "basic spell", but Harry added, "Never doubt simpler spells. This one kept me alive."

He turned to Fred and George. "Seriously, guys, could you get this stuff off Ron's face?"

Ron nodded wildly in agreement, afraid to open his mouth in case the stuff would turn him into an animal or something.