This article reports how "value-added" measures that track the "value" that schools add to individual students' learning over time are increasingly popular with educators and policymakers. Some view the methods as an antidote to accountability systems that focus solely on getting children to a specified achievement level on a state test,…

The proportion of public schools' meeting their prescribed achievement targets under the No Child Left Behind Act appears to have fallen slightly in the 2005-06 school year, while the percent classified under the law as needing improvement increased. The trends bear out earlier predictions that schools would find it increasingly hard to show…