For many years, most of the problems of American public education have been described in terms of “achievement gaps.” This framing, and the education policy approaches that build from it, have much to recommend them. The framing begins from the incontrovertible premise that students from historically underserved demographic groups often have limited access to high-quality educational opportunities. This core, systemic inequity drives gaps in student achievement between students from these groups and privileged students. As such, those achievement gaps—as measured by academic assessments—serve as beacons guiding efforts to improve American public education.
But policymaking based on an “achievement gap” approach to educational equity isn’t without problems. There’s nothing wrong with the goal, of course: equitable opportunities and outcomes for underserved students are elemental, if often perjured, promises of American public education. Rather, it’s that achievement gaps are only effective illustrations of structural inequities when they’re measured appropriately...