More than a quarter of Montgomery County elementary and middle schools failed to meet the "No Child Left Behind" achievement standards this year, according to results released Tuesday by the state education department.

Five middle schools entered a probationary "school improvement" phase, after failing to have met the federal "adequate yearly progress" standard, or AYP, for two years in a row. Nine of the county's 38 middle schools are in improvement, along with Daly Elementary School.

In neighboring Prince George's County, 53 elementary and middle schools are in the improvement phase, including 30 that have failed to come out of it for five or more years. Schools that have been in improvement for five or more years are subject to a variety of major overhauls.

"The majority of MCPS schools made AYP and those that didn't are not failing schools but simply have areas where the teachers, staff and students must put some focused effort," said Montgomery Superintendent Jerry Weast. "We will work closely and collaboratively with these schools to address these areas in the coming year."

The high failure rates reflect, in part, the increased expectations placed upon schools as they approach the federal legislation's 2014 deadline to make every student "proficient" in math and reading.

In 2003, the state set achievement targets for each school and for each subgroup within the school based on race, poverty status and special needs. The targets were meant to ensure schools eventually met the goal.

"The closer we come to 2014, the harder it becomes for a school to meet these targets for all subgroups," wrote Maryland Superintendent Nancy Grasmick in a memo to the state school board.

In Montgomery, half of the schools that missed meeting AYP did so only because of one failing subgroup.

County AYP results were released the same day as scores on the state's standardized math and reading exams. Montgomery County elementary and middle school students posted results consistent with their 2009 performance.

Prince George's students made strong gains at all but the eighth grade level, especially in reading. Even so, the beleaguered school system remains, with Baltimore City, among the worst performing districts in the state.

At fourth grade, 91 percent of Montgomery students scored either "proficient" or "advanced" on the math test, equal to 2009 and placing the district 17th out of 24 systems in the state. In Prince George's, 83 percent of fourth graders met the same standard, up from 81 percent in 2009 but still the lowest of the state's school systems.

In eighth grade, 75 percent of Montgomery students passed the test, up from 74 percent in 2009. In Prince George's, only 41 percent made the mark, down from 43 percent in 2009.