When a state grades or punishes it schools for having too large a gap between the systems low achievers and the high achievers, what incentive exists for the school system to push the high achievers??? Check out this article from US News and World Report that addresses this topic... One that is close to my heart...
"Education Reform May Leave High Performing Students Behind"
http://www.usnews.com/news/articles/2013/11/08/education-reform-may-leave-high-performing-students-behind?page=2
