Last week the National Center for Education Statistics released the latest NAEP long-term trend assessments in reading and mathematics. The assessments were first administered in 1971 (reading) and 1973 (mathematics).

Average reading and math scores for 9- and 13-year-olds increased, but scores for 17-year-olds remained flat. It’s not clear why. As others have observed, it appears that early gains are “washing out” or fading as students progress through high school.

Regardless, I am confident that advocates of No Child Left Behind will take credit for the increases, which occurred between 2004 and 2008. I suppose it is possible that the accountability measures built into NCLB had something to do with it, but there are a number of other plausible explanations.