It wasn’t long before Roberto landed in Peggy Salazar’s office to discuss his disruptive behavior and poor academic performance. The acting principal of Oak View Elementary School coaxed some information out of her young student that helped to explain why he was struggling. Salazar learned that Roberto’s parents were divorced. Sometimes he lived with his mother, sometimes his father—it depended upon whose financial situation was more stable at the moment. (Both parents work several low-paying jobs.) When Roberto switched parents, he also switched schools. As a result, he’s attended four schools just in the last five years.

Peggy Salazar’s school is filled with kids like Roberto. The majority are African American or Hispanic; 84 percent qualify for free or reduced-price lunches; and a quarter have limited proficiency in English. More important, they come and go as frequently as Roberto does. Of the roughly 300 students at Oak View Elementary, only one in four arrived from the local feeder school; the rest came from elsewhere. Which is to say, Roberto’s situation is not the exception, but the rule.

This problem plagues principals like Salazar, whose schools are judged by how well students perform on standardized tests. Oak View’s fate hinges on the Maryland School Performance Report, a test that includes the scores of transient students like Roberto, who may not have been in that school last year and may not be around next year. Salazar was never able to get Roberto to improve his classroom performance. “I am not going to be here long anyway, because I move a lot,” he reasoned. “My report card doesn’t even catch up with me.” With standardized testing poised to play a more prominent role under President Bush’s education plan, the problem of how to reach students like Roberto without punishing principals like Salazar is growing more acute.

Bush modeled his education plan after the one he oversaw as governor of Texas. It’s premised on the notion that annual testing is the best way to hold schools accountable for teaching kids. Schools that perform poorly will gradually lose federal funding. Those that don’t improve will be shuttered. In order to “leave no child behind,” as Bush likes to put it, every child is tested annually. But scores for certain groups of kids—minorities, poor, migrant farm workers, and the disabled—are measured independently. That way, educators get a clear picture of who’s learning and who isn’t. Schools can’t mask an underperforming subgroup simply by factoring its scores into the broader student body’s, and they can be held accountable for making sure that all groups improve.

The Texas system is a good foundation, but it has one overwhelming flaw: As Roberto’s case demonstrates, annual tests can’t distinguish who is learning and who isn’t learning if they don’t take account of the fact that the students being tested in any given school differ from year to year.

The bad news about the education plan Bush brought to Washington—as well as those passed by the House and Senate—is that the tests and the reporting requirements they mandate don’t make this crucial distinction. Many schools, particularly the low-income schools Bush promised to target for reform, don’t teach the same students from month to month, much less from year to year. Without measuring a school’s mobility rate, standardized tests can’t possibly offer an accurate snapshot of students’ learning progress. So principals like Salazar—who may be doing an excellent job teaching those children under their purview all year—are unfairly blamed, while parents whose kids attend the same school get a distorted view of the school’s performance. Worse, if the poor performance of transient kids drags down such schools, an otherwise competent school could be shut down, forcing students like Roberto to move on once again.

Transient students are a widespread problem. A General Accounting Office study found that one out of every six third-graders has attended three or more schools since entering the first grade. The problem is more acute in the inner city. A study of Chicago students revealed that fewer than half who entered school in first grade attended the same school in fourth grade. Some schools retained fewer than 30 percent of their first-graders. A New York Times investigation found that 40 percent of the students in a typical New York City classroom changed schools over the course of the year. When classrooms resemble bus terminals, it’s easy to see how most standardized tests fail to accurately measure school performance. In the real world, many kids are just passing through.

Not surprisingly, transience takes a toll on students, whose poor performance on tests can have little to do with their teachers’ effectiveness. Students who change schools frequently usually aren’t high academic achievers. Highly mobile students at all income levels generally test below their grade level in reading and math.

Kristine Emig’s fourth-grade class at Oak View Elementary School has plenty of experts on student mobility. In fact, Emig’s students could give the White House a quick synopsis of the shortcomings of its education plan. Some students’ parents had been relocated for a job. Others had been forced out of an apartment or had sought more child-friendly housing. Even success can result in displacement. Two parents who’d finally saved enough money to put a down payment on a new home had to move their kids to a new school district as a result.

All this moving around is disruptive for students. Carlos had already changed schools three times, explaining that when he arrived at his last school, he was way behind because the school taught a different curriculum. “My new school was too hard,” he said, “so we moved again.” Steven, who’d also changed schools three times, had the opposite problem. “They were learning how to write letters and I had already done that,” he said. One common trait among mobile students is that their grades declined when they changed schools. Often, they had a difficult time getting extra help. That’s not unusual. The GAO found that mobile students are less likely to receive Title I federally funded special education services than their more stable classmates. They’re also more than twice as likely to repeat a grade. The problem is closely tied to class. Children from the poorest households, who are forced to change schools frequently, are the most likely to drop out.

Transient students also take a toll on teachers, who find that bringing them up to speed can be difficult. “A lot of times, they have not had a lot of consistency in what they have been learning,” Emig said. “It hasn’t stuck with them, especially if they are worried about making new friends and adjusting. One of their first concerns is making new friends and fitting in. [Their classroom performance] gets put on the back burner.” By the end of a school year, a teacher like Emig may only have been able to teach the full curriculum to three of every five students. The stress this causes helps to explain another problem with transience: Schools with high turnover rates for students also have high turnover rates for teachers. So not only do many annualized tests wind up measuring different students, they also measure different teachers.

Education reform can factor in student mobility and still hold schools to high standards. But to do so, standardized tests must acknowledge the problem. For states to help mobile students, the federal government must take the first step. The centerpiece of Bush’s school accountability plan is the Adequate Yearly Progress test—a mechanism which, in theory, is ideally suited for this task. The education bills passed by the House and the Senate each maintain this structure. They “disaggregate” the scores of minorities, the poor, the disabled, migrant farm workers, and those with language barriers (the Senate bill adds gender), separating their scores and requiring progress in each category so that schools can’t ignore them—but neither bill accounts for mobile students. This makes no sense. Tests show that, at all income levels, mobility is at least as great a predictor of subpar performance as race, poverty, or disability. (If you’re wondering how the president and Congress could have made such an oversight, ask yourself when you last heard anything from the “Transient Student Lobby.”)

Principals know that transient students bring down their school’s test scores, and the savviest long ago figured out sub-rosa ways of masking the effect (such as shuttling transient students into special education classes). But such gaming of the numbers punishes schools that don’t do it, which does little to aid transient students. The right kind of accountability system, says Andrew Rotherham, education policy director at the Progressive Policy Institute, will “measure the progress of all students and get them the help they need, without creating perverse incentives for schools by holding them accountable for factors they cannot control.”

The principle of discounting mobile students isn’t a new one. The federal government already allows the test scores of students who move from one state to another during the school year to be excluded from a school’s accountability requirement—an accommodation demanded by the nation’s governors and others. States such as Arkansas and South Carolina already allow schools to separately count the test scores of students who have moved in or out during the year. The benefits of making all schools disaggregate the the test scores of the transient from the non-transient are numerous. States will be able to identify better schools with high mobility rates and perhaps direct more resources to those schools. Parents will have a more accurate idea of which schools are doing a good job of teaching the children they actually have nine months to teach, and which aren’t. And if Congress doesn’t make the mistake of letting states and school districts totally off the hook for the performance of transient students, then policymakers will have more incentive to help these kids adjust better. In an age when credit-card information is instantly available online, there’s no reason that Roberto’s report card should arrive at his new school months after he does.

Policymakers should also experiment with programs that help parents avoid putting their children in different schools every few months. A study of Chicago schools showed that the average student moved just three miles. The Census Bureau’s annual mobility report confirms that this pattern is the norm nationwide. With proper funding, districts could expand bus service so that students who make short moves could remain in the same school.

But none of this will happen unless the House-Senate conferees start taking as much interest in student mobility as they do in race, income, and gender. That way all students—even those who don’t stick around for long—can get the education they deserve.

Thad Hall is a program officer at The Century Foundation.

Thad Hall

Thad Hall is an Associate Professor of Political Science at the University of Utah. He is the author of Evaluating Elections: A Handbook of Methods and Standards (Cambridge UP 2012).