The ed reform crowd genuflects before the National Assessment of Educational Progress (NAEP), the holy grail of testing. And in most cases, its deification is appropriate. But when comparing charter schools to traditional public schools, the holy grail becomes a Dixie Cup. The latest round of NAEP scores shows that charter students probably are performing at a slightly lower level than their non-charter peers, though, when one controls for race and income, the differences are negligible. More troublesome, NAEP only provides a snapshot in time, so it's impossible to know from these data whether charter schools students are gaining or lagging their district school peers. (Most rigorous studies show that they are making gains.) Fordham President Checker Finn summed up yet another problem with NAEP charter-school data: "I'm not very interested in the average performance of charters.... The word 'charter' signals so little about them, and the diversity within that universe is at least as great as the diversity outside it." In short, it's incorrect to treat "charter schools" as a unique entity or homogeneous mass. It makes about as much sense as trying to form a single impression of pastry shops or pizza parlors.
"NAEP Gap Continues for Charters," by Erik W. Robelen, Education Week, May 19, 2008