This spring, the school in affluent Tarzana began using a lottery for applicants from outside the neighborhood. Within hours, more than a dozen children were on the list.
On average, the children started out as high achievers but year after year lost ground on the state's standardized tests, according to a Times analysis of scores from the 2002-03 through 2008-09 school years. Nearly 90% of schools in the Los Angeles Unified School District saw more academic progress.
Several other respected elementary schools, including Topeka Drive in Northridge and Third Street in Hancock Park, also had poor results.
At the same time, some of the biggest gains came on campuses in low-income areas, schools often considered failing by state and federal standards.
The school whose students improved most? Maywood Elementary southeast of downtown Los Angeles, where virtually every student qualifies for free or reduced-price lunches and almost half are still learning English.
Parents — and even principals — don't know this because the district doesn't measure progress in this way, although it could.
Schools such as Wilbur shine under the current measure of academic success — the all-important Academic Performance Index — based on students' achievement level on standardized tests. But, as state data show, such measures largely reflect students' advantages outside school, not what the school itself is contributing to their learning.
The API obscures the fact that students at Wilbur had the potential for further growth that went unrealized. Instead, they tended to slip every year while those at other esteemed schools in well-off neighborhoods made great strides. It also obscures the gains in schools in impoverished areas.
A similar story is playing out across the country.
"We're measuring who is in schools rather than how effective the schools are," said Helen Ladd, a professor and testing expert at Duke University.