Are we talking about trouble making kids, or kids who aren't going to ace their exams? Your numbers are all invented whole cloth; please don't try to math with

Are we talking about trouble making kids, or kids who aren't going to ace their exams? Your numbers are all invented whole cloth; please don't try to math with them. More precisely: Why should I believe that the remaining kids learn more? In my experience, everyone learns more when they teach, as it forces them to shore up their assumptions. (When you learn something yourself, you learn one wrong way to do it. When you teach, you learn thirty wrong ways.) Having kids who think differently around for peer exchange is then a good thing overall. The struggling kids have stronger peers around to teach them, and the stronger kids have more chances to teach.