82% labeled "failing"?

According to Secretary Duncan's testimony before Congress today, 82% of schools in the United States could be labeled failing this year:

Duncan pointed out, however, that current federal law requires states and districts to implement the same set of interventions in every school that is not meeting AYP, regardless of the individual needs and circumstances of those schools.
Duncan explained that, in generating the estimate, the Department assumed that all schools in the country would improve at the rate of the top quartile. Under this assumption, and factoring in four years of data, the percentage of schools that are not meeting AYP could rise from 37 percent up to 82 percent.

Education 101: if 82% of the class failed something, there's a decent chance it's the assessment that's got it wrong.
UPDATE: Looks like Duncan's estimate (which was conservative, by the way) may have finally lead to a difference with the DFERs.