The challenge
Achievement gaps between groups of students were large and often hidden in averages.
The case
The No Child Left Behind Act of 2002 required US states to test students every year in reading and math, report results by student group, and impose escalating consequences on schools that missed progress targets. Researchers found it raised math scores, particularly for younger and disadvantaged students, but had no detectable effect on reading. Critics documented narrowing of the curriculum and 'teaching to the test', and most states were eventually granted waivers before it was replaced in 2015. Dee and Jacob estimate that NCLB raised fourth graders' average math performance by an effect size of 0.23 by 2007, using national NAEP data.
Why the results were mixed
Public, disaggregated data exposed gaps that had been hidden, but rigid targets that almost every school would eventually miss lost credibility. Accountability works better with realistic goals and support, not just sanctions.
Sources
Spot an error or know a better source? Tell us