Don't get me wrong, test scores mean something and educational accountability is a good thing. But unquestioning belief in all things data-driven sometimes just gets silly.

New York City has the latest example of that, with a reductionist "report card" for schools that already had gained a certain rep for being out of touch with reality. Now, the New York Times reports that a beloved elementary school that has been through a remarkable turnaround and won public praise from top school officials received an F on its latest city report card. The "grades" rely mainly on how much test scores improved, and where they were in comparison with schools that have similar demographics.

In the case of Public School #8, it appears there might be a problem with the way the data are compiled; the test scores are for students in  older grades, but the demographics are for the entire school. At this particular school, where middle-class families have only recently begun enrolling their children--something the city desperately wants--this skews picture.

The report cards are serious stuff; bad grades can mean replacing a school's administration. But if school honchos want to use the numbers to humiliate schools and punish principals, they'd better start learning to do more complicated math. Reducing a school to one overall grade is misleadingly simplistic at best, cute fodder for headlines but not for helping parents or the public understand schools. Los Angeles Unified is heading toward school report cards; let's hope these will give us some real information instead of becoming convenient but misleading symbols of accountability.