The law, though, was deeply unpopular with many educators and parents. Critics said it put an outsize focus on testing, pushing schools to teach to the test and spend less time on other important subjects, like the arts or social studies. In 2015, Congress replaced it, and many states dialed back on requirements.
Like many who have studied the law, Brian A. Jacob, professor of education policy at the University of Michigan, showed that it increased test scores but had problematic elements.
"It was not a cure-all, but I think it really did improve student achievement," he said. "There's evidence that school accountability does change behaviors of teachers and administrators and probably parents and students."
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