In 2015, Louisiana switched to standardized tests aligned with the Common Core standards, which were far more rigorous than the old tests. It began the process in 2014, when it first moved its tests in that direction, and it continued to alter the test after 2015. Not surprisingly, starting in 2014, what had been a steady rise in proficiency leveled off. Education reformers began to fear that this plateau revealed waning effects of the move to charters, rather than just the impact of tougher tests.

But a new report by the Stanford Center for Research on Education Outcomes (CREDO) focused on student growth scores reveals that New Orleans’s progress has continued.