A decade after passage of a federal law requiring statewide school assessments, nearly 90 percent of Maryland's elementary students are passing their reading and math tests, but that success does not continue when students hit middle school.

Last school year, 69 percent of students passed the math tests in eighth grade, up nearly 3 percentage points from the year before. Achievement in reading was at 79.8 percent.

Middle school math scores were the low point in the latest Maryland School Assessment results, released Tuesday by the state, and are likely to be a focus of attention for a number of school systems in the coming months.

Lillian Lowery, the new state school superintendent, said overall the results "show steady improvement" but also noted that in addition to the lower math scores in higher grades, minorities, special education students and those who don't speak English as their first language continue to pass at far below the rate of the rest of the population. That achievement gap continues in some areas despite overall gains in the past decade.

"There is nothing to suggest in these results that we can sit back and relax," said Lowery, who has been on the job for just over a week.

Baltimore City, in particular, showed little progress. After test scores rose from 2000 to 2009, the city stalled, with scores remaining essentially flat over the past three years. While Prince George's County and Baltimore were the lowest-performing in the state, Prince George's has significantly outperformed the city in the past two years.

The city's scores are now generally 25 to 30 percentage points below the state averages. Baltimore increased its scores in math and lost ground in reading. While city schools CEO Andrés Alonso promoted the system's double-digit gains during his tenure, he also acknowledged that they're not good enough.

"It takes time for schools to improve," Alonso said in an interview. "I'm going to look at the results this year and create a sense of urgency. But it will be a sense of urgency over time."

About 67 percent of city students performed at proficient or advanced levels in reading, a decline of roughly 2 percentage points from last year, with decreases at the elementary and middle school level.

The system's traditionally weak math scores rebounded this year from a 5 percentage-point decline in 2011. The proportion of students who scored proficient or advanced in math rose slightly, by 2 percentage points, to 63 percent. But the passing rate in middle school was much lower: Only 39.5 percent of eighth graders passed.

Baltimore County saw small increases in most subjects in most grades. The county's elementary students scored at about 90 percent in both reading and math, and its African-American students are closing the achievement gap with other students. But in middle school, only 74 percent of students passed in math.

Baltimore County school Superintendent Dallas Dance said he is pleased with the elementary school performance and noted that one elementary school, Rodgers Forge, had 100 percent of its students passing the tests. But, he said, he is concerned by the lower scores at the middle schools.

Howard County continued to increase scores by small increments in all but a couple of grades. About 95 percent of the county's fourth- and fifth-graders passed the reading test. Middle school scores were inconsistent, with some grades going up and others down.

Anne Arundel County also made gains in most subjects. At least 90 percent of elementary students are passing both reading and math at each grade.

This year for the first time, Maryland schools are being held to a new, more flexible standard under federal law. The original one-size-fits-all approach of the federal No Child Left Behind law required 100 percent of student in the country to be proficient in reading and math by 2014, which left a growing number of schools labeled as failing.

Now each school in Maryland, which was granted a waiver from the law, will have its own targets. Schools will expected to cut in half the proportion of students who aren't proficient by 2017.

Under the new system, 85 percent of schools meet the federal standard. Last year, far fewer met the mark. The statewide tests are given annually to students in the third through eighth grades.

Lowery said middle school math teachers generally do not have the same depth of knowledge of their subject as other teachers — and that could have affected the scores. Historically in Maryland, middle school teachers only needed to be certified to teach in elementary schools, though teachers are now required to get additional training in their subject.

It is a concern shared by Dance, who took over as head of the school system a week ago. He said he requested that his staff give him information about training the county's middle school math teachers. While gains were made last year, having only 68 percent of eighth-graders passing the math test is too low, he said, adding that the county also is rewriting its curriculum to match that of the more rigorous standards coming later this year.