"Alaska, Delaware and North Carolina, for instance, permit charter schools to give admissions preference to students who demonstrate interest in their particular educational focus. Some schools use that leeway to screen for students who are ready for advanced math classes or have stellar standardized test scores."

Reminds me of the charter in our area which REQUIRES calculus in order to graduate. So they are effectively cherry picking students who are motivated and bright enough to complete calculus. The school is grades 6-12. In the middle school, many kids have IEPs but I noticed that in the high school, none of them do. So is the school making things so difficult for kids with special needs that they drop out and go back to their regular public school? Or are they getting kids off IEPs? What turned me off was that at the presentation they stated that they give kids 2 1/2 hours of homework per night, even in the middle school. So they are cherry picking only kids who are highly motivated. From reading reviews from parents/students, they give poor grades to the students who don't perform, those kids become demoralized, and drop out. The charter is one of the top rated schools in the state, but that's because they have only good students, not necessarily because their instruction is all that spectacular.