Free! THE OPPORTUNITY GAP app (not to be confused with the equally impressive Gap App Challenge) is an ambitious project from ProPublica which cross-references NCES data on the percentage of students receiving free/reduced price lunch with Advanced Placement stats (among others) from the Dept of Ed's Office of Civil Rights to make inferences around poverty and educational equity. Some inferences are quite informative, if not disturbing. Take Oklahoma, for example. In the Sooner State, "for every 10-point increase in the percent of low-income students, the percentage of students enrolled in AP drops by three points." By contrast, a 1% increase in Massachusetts' low-income students yields a 6% drop in AP enrollment.