The arithmetic of Duncan-style school "turnaround"

They used to call it "reconstitution". You know, the one where they fire all the teachers and make them reapply for their jobs, but rehire no more than half of them anyway, leaving the rest to twist in the wind. So, this is the story of a Chicago school that was closed and then reinvented as a "turnaround". Look carefully at the numbers used to justify first the closing of this school, and then the status change from unaccaptable to improving:  http://www.huffingtonpost.com/matt-farmer/chicago-collins-academy-turnaround_b_1159465.html