Another year's test scores are here. So, how are California's students doing? Lately, that depends on whom one asks.

State Superintendent of Public Instruction Jack O'Connell would point to the "the outstanding [Academic Performance Index] results" showing "widespread gains." But the accountability reporting system under the federal No Child Left Behind Act paints a less positive picture — only 56 percent of California schools met their Adequate Yearly Progress, or AYP, down from 64 percent last year.

Who's right? With all these acronyms, it is time for a refresher on the important difference between California's API and the federal AYP. When calculating API, the state lumps all students together and assigns each school a score between 200 and 1,000. AYP, on the other hand, is designed to measure whether all students in a school — of every race, social-economic status, those with special education needs and English learners — are making enough progress each year.

O'Connell argues that API is a better way to gauge school progress and has urged the federal government to change its accountability measurements. On the contrary, AYP provides a better picture because it spotlights those students stuck at the bottom.

More than 5,000 California schools managed to increase their API but did not improve achievement for all subgroups. By and large, those at the bottom are racial minorities, English learners and those from socially and economically disadvantaged backgrounds. With API, a low percentage of African-American or Latino students scoring proficient or above in mathematics and English would not be flagged so long as the school as a whole was improving.

Improvement on California's API is certainly a good thing, but AYP is one of the only tools we have to close the persistent and inexcusable achievement gap. In Oakland, Jorge Lopez, principal of Oakland Charter Academy middle school, a public charter school, tells a story that illustrates the importance of AYP.

The scores at the Oakland Charter have always appeared high, but the school had never met its AYP. This tipped off Lopez to look for problems when he became principal. As it turned out, the feeder elementary school, whose students were scoring high on state tests, was inflating Oakland Charter's scores. Unfortunately, some students who came in testing "advanced" in Language Arts left the school testing at only the basic level. Behind the scores, the school was failing its students.

Since Lopez has been in charge, he has made student achievement growth by all students a top priority, thereby fulfilling AYP. Lopez says there is a tendency in the media and even by researchers to ignore the bad news contained in AYP in favor of the seemingly good news brought by the API. He says, "It's like a guy who's been starving and sees a buffet. And he says, ‘Oh my God, this is the best food.' Because you see the raw data and you say, ‘Wow, this is great.' But you don't realize that you're eating things that are high in fat and cholesterol. That's the AYP, that's the breakdown. The AYP says wait a minute, slow down, you're going to kill yourself."

All things considered, the API is not, as Jack O'Connell believes, a better approach. And the federal government should not change its accountability measure. If California legislators want a true picture of how all students are performing, they need to focus on AYP.