A very small number of students in a subgroup monitored for AYP can put a school into improvement status.  The idea behind this was to spotlight the kids who need the most help and push districts to allocate the resources they need to reach proficiency on state tests.

Of course, no parent wants to send their kid to a failing schools, and superintendents want as few of them as possible. Educating the kids most in need is one way to keep schools out of improvement. Another way to reduce the ranks is to take all the problem kids and concentrate them in one or a few problem schools - and then be in a better position to say it's impossible to bring all those kids up to standard on NCLB's timeline.

Your editor is not saying that was deliberate policy in St. Lucie County, Florida, but the outcome was at least forseeable from what Cara Fitzpatrick says in today's Palm Beach Post.

 New attendance zones established in the St. Lucie County School District this school year have done what some critics feared: concentrated many of the district's poor and minority students into Fort Pierce schools.... As a result, more than half of the city's schools saw devastating drops in school grades this year - one elementary school plummeted from an A to an F - and an almost entirely new population of students walking down the halls.

On the other hand, concentrating these kids may make it easier to serve them with SES and school improvement funding. From a market standpoint that may be advantageous, but it doesn't suggest that the district really has these kids' best interests at heart. It really looks like they'd like to put those kids out of the sight of other kids' parents, and maybe increase the odds of getting their kids' schools out of improvement.