Because these students may be learning qualitatively differently, meaning that leaving them in middle-road classes will not teach them as effectively. And more

Because these students may be learning qualitatively differently, meaning that leaving them in middle-road classes will not teach them as effectively. And more importantly, because leaving gifted kids in unchallenging classes often causes them to burn out and get turned off on school and learning entirely. I've seen it happen, and it's so sad.