At the end of each day, when most pupils at Remington Elementary School in Santa Ana head home, about 100 children stay behind for more work on their reading, writing and math skills.
For Principal Edna Velado, deciding which of her nearly 600 pupils would attend the after-school program was difficult.
Last year, she filled those seats with her poorest-performing students -- many of whom spoke little English or were years behind in learning.
This year, confronted with a federal law that requires her to dramatically increase the number of children passing standardized tests, Velado made a different call.
Students who had nearly made the mark on last year's tests, she reasoned, stood the best chance of clearing the hurdle this year. Those kids, she told her teachers, would receive the additional 90 minutes of instruction -- even though they weren't the ones most needing help.
"Our job is to educate all students, and we do that," Velado said. "But in order to avoid the sanctions of this law, we need to [make choices] that will make the most impact for the school. There are numbers we have to reach."
In her decision and her frustration, Velado is hardly alone.
As teachers and principals throughout California and the country struggle to satisfy the increasing demands of the federal No Child Left Behind law, education experts and school officials say they are paying increasing attention to the middle-of-the-road students who have fallen just short of test requirements.
This new focus on so-called "cusp" or "bubble" students, many experts say, is an unintended consequence of a law that emphasizes test scores and defines success in narrow terms.
The 2-year-old federal law -- a centerpiece of President Bush's domestic policy -- aims to improve schools by requiring states to administer annual math and English exams to all students.
The law mandates that by the 2013-14 school year, all students must at least score at a "proficient" level.
States were left to set the incremental targets that schools would have to reach each year to meet the law's ultimate goal.
Under the federal law, schools get no credit for improving test scores -- and can be designated as failing -- unless they meet the strict annual improvement targets set by each state.
"There are a lot of perverse incentives built into this law," said Gary Orfield, a Harvard University education professor. "It has put tremendous pressure on people to find what shortcuts they can.... Because there is only one data point that determines how a school is doing, there is no incentive to work with the kids who are on the top or on the bottom."
Eugene Hickok, deputy secretary in the U.S. Department of Education, acknowledged that "as a fact of human nature, [teachers and principals] will focus on the margins where they have the chance to make the most impact."
But he disputed the claim by Orfield and others that the law leaves school leaders no choice but to work with cusp students over others.
Schools, Hickok said, must attend to all students equally in order to ensure that the worst-performing students are steadily improving and eventually are able to pass the tests.
"The law is forcing schools to get kids to proficiency. It does not tell them how to get there," he said.
Schools that receive federal funding for serving a large percentage of underprivileged students have the most at stake. If such a school falls short of the improvement targets two years in a row, a series of increasingly serious interventions and sanctions kick in that can culminate with principals and teachers being replaced or control of a school handed over to outside managers.
This year, the bar is rising sharply in California. About one quarter of each school's students must be proficient by year-end -- an increase of nearly 11% from previous years.
A recent Los Angeles Times analysis showed that more than 1,200 schools -- about 13% of the state's 9,000 public campuses -- are unlikely to hit the target this year. And based on the last two years of scores, 3,500 schools would probably be deemed as failing in 2008, the analysis showed.
Teachers and principals say that in the face of the sanctions, they have no choice but to try to meet the federal standards. For many, that has meant poring over test data to identify the students approaching proficiency in hopes of raising their scores.
Like Velado at Remington in Santa Ana, Principal David Diaz of Independence Elementary in South Gate set aside funds this year -- in his case about $80,000 in overtime -- so teachers could work an hour after class each day with their cusp students.
Tony Delgado, principal at Van Nuys Middle School, said he is well aware of the importance of raising his cusp students so his school can make the grade. He said that in the weeks before the standardized tests, he, along with vice principals and counselors, plan to meet with them in small groups to review test-taking strategies.