The annual troubles of the Lewiston school system’s diversity and the strict standards of No Child Left Behind are growing worse. This year, four schools failed to make “adequate yearly progress,” which some consider equal to a “failing school.”

Yet the one-size-fits-all approach of the federal guidelines cannot allow for such a designation. When it comes to Lewiston, NCLB only reveals what’s known: The learning needs of the city’s immigrant population are a challenge.

About 20 percent of Lewiston’s students are considered “Limited English Proficient,” under NCLB, but this blanket definition fails to account for the demographics that are peculiar to this school district and this city.

Almost 70 percent of these students have been enrolled in school for fewer than three years, across the age range. There are immigrant teenagers coming to Maine who are illiterate in their native language, much less with a workable knowledge of English.

And there are students for whom Lewiston is the first organized education they’ve experienced. To expect students from such varied, distressed backgrounds to make the quantum leaps necessary to master American standardized testing is untenable.

This is the source of Lewiston’s quandary. Its demographics are challenging enough – most of its schools have higher-than-average populations of economically disadvantaged students.

Combining this economic disadvantage with the rising amounts of immigrant students, however, and the problems meeting NCLB standards rise exponentially.

It’s an uncomfortable situation, too, because federal guidelines compel the district to tell parents why their school failed to make “adequate yearly progress.” This has potential to scapegoat immigrant students for the school’s designation, though it’s not their fault.

The fault lies with No Child Left Behind. In striving to ensure all children have equal educations, the program has created inflexible standards that prevent districts with unique situations, like Lewiston, from fair appraisals.

It is the reason the National Conference of State Legislatures, back in 2005, recommended Congress weigh limited English proficiency students by measures that emphasize annual progress, instead of basic benchmarks.

This would help Lewiston, as the educational progress of immigrant students is proven.

Longley School, for example, saw its limited English proficiency students improve their reading scores by more than 10 percent from 2007-08, which was a real success of instruction that is largely under-recognized by NCLB.

For districts such as Lewiston, NCLB is almost useless because it cannot evaluate its schools’ performance adequately. The challenges are unique and the benchmarks too static.

It’s nobody’s fault but the law’s. And the law should be changed.