In 2008, the official dropout rate in Alexandria City schools leapt from 3 percent to 11 percent. In neighboring Arlington, it jumped from 2 percent to 9 percent. Fairfax saw its rate bump up to nearly 6 percent, from less than 2 percent one year earlier.

The reason for the changes were not sudden shifts in student behavior, but a change in how Virginia schools tracked students, and therefore how they calculated rates. And by all accounts, the newer, higher rate is much more accurate.