Relatively obscure federal rules are lifting 34 Utah schools off No Child Left Behind's dark side, and more could follow in the coming weeks.

Twenty-five Granite District schools and nine Alpine District schools that were identified last month as failing to make "adequate yearly progress" on math and language arts tests now are set to pass federal muster based on rules allowing test scores to be averaged over three years, the Deseret Morning News learned Friday.

But it's uncertain whether all school districts knew about this rule or another one regarding students with disabilities, which also stands to alter the number of schools achieving AYP, state associate superintendent Judy Park said.

"The place where it is right now, is some districts have appealed for reasons that others haven't," Park said. "We (need to) make sure there's equity across the state."

She is working to set up a meeting with district bosses to go over the rules and discuss their options.

No Child Left Behind expects all students, regardless of race, income or disability to be able to read and do math well by 2014. States must issue annual AYP reports measuring progress toward the goal. Schools must have 95 percent of students participating in tests, plus meet state testing goals for all student groups, broken down for ethnicity, disability and income. If any segment fails, the whole school fails to meet AYP standards.

Last month, the State Office of Education reported 256 Utah schools failed to make AYP.

School districts had from Aug. 15 to Sept. 15 to review test scores and AYP designations prepared by the state. Schools can appeal, and district superintendents can grant the appeals, for two specific reasons: A calculation or data error or an extreme circumstance, Park said. The state goes through granted appeals to ensure they meet those standards.

But other rules are coming into play this year.

Under a federal rule, schools not making AYP could average their test scores or their participation rates over the past three years. If the average meets the mark, then the school can use that to clear the federal hurdle.

"The purpose of that provision is actually quite sensible," said Christine Walquist, testing director for Davis School District. "When you have very small (number of students in a student group) ... then there can be radical differences in performance based on the specific characteristics or needs of individuals in the subpopulation."

Averaging can give a more even-handed look over time at how that group is doing.