Today’s big news is what the Times terms “the Robin Hood effect” of No Child Left Behind: the reality that as schools have redoubled their efforts to help low-performing students get higher test scores, more successful students have lost out. This reality is the subject of a new report out of the Fordham Foundation, titled “High Achieving Students in the Era of NCLB” (pdf), which concludes that new accountability systems invariably increase pressure most for increased performance among the lowest achievers and that despite their widespread belief in equal time for all students, teachers make their weakest students their highest priorities. Since 2000, the report finds, the lowest-scoring students in states with test-based accountability systems increased their scores on federal tests by almost 6 percentage points, while the highest-scoring kids boosted their scores by less than 2 percent.

Two questions: First, doesn’t the conclusion suggest that NCLB is doing its job? After all, we’re not closing the achievement gap when everyone improves equally — we’re just moving it.

Second, and more seriously, Eduwonkette has written before about the need for “interval scaling” in analyzing the implications of test scores — that is, in recognizing that movement at the low end of the spectrum is easier to accomplish than movement at the top. It’s not clear to me whether the folks at Fordham took interval scaling into account. If not, the numbers suggest to me that it’s possible that both sets of students may have derived equal benefit from their teachers and schools — but that equal benefit does not correlate with equal score gains.

Despite the unanswered questions, the blogs are abuzz today with suggestions about how NCLB can be tweaked to provide incentives to help high-performing kids, given that the law’s incentives for teachers to help their weakest students appear to have been effective. Chad Aldeman at the Quick and the Ed, the Education Sector’s blog, writes that he hopes the report opens the door to value-added assessment becoming an accepted form of accountability under NCLB. Like many others, he wants to see schools evaluated on the basis of how successful their teachers are in moving students at least one grade level in one school year.

A variation on value-added was part of the progress reports that the DOE issued for the city’s schools for the first time last year. More than half of each school’s letter grade was based on what the DOE termed “student progress”: a combination of whether teachers moved students one grade during the year and “extra credit” based on the improvement of subgroups within each school, such as black students, the lowest third of students, and kids in special education. But in addition to being statistically flawed, the progress reports were poorly received because they gave low grades to high-performing schools and high grades to low-performing ones, including many that are on the state’s list of failing schools and a few that are on the verge of closing. The progress reports contained some useful information — information that many education pundits today say has been missing from the national conversation about achievement — but their reception underscores the fact that data ought not be associated with consequences in order to be illuminating.

Finally, in response to the Fordham report, Amy Wilkins of the Education Trust makes the important point in the Times that schools don’t actually have to pick between helping weak and strong students — a successful school will offer opportunities for both kinds of kids to improve. In some pockets of the city, such as in Brooklyn’s District 15, principals, aware of the targeted resources made available for low-scoring students, have made a deliberate effort to create special opportunities for all students by introducing what’s known as the Schoolwide Enrichment Model. Under this model, promoted by University of Connecticut professor Joseph Renzulli, all students choose a topic or skill of interest to them and pursue those topics in small, mixed-ability, and often mixed-age groups. Of course, like all programs, SEM can be implemented well or botched, depending on the school. But it offers a low-cost model under which teachers might direct attention to students with all levels of ability.