Baltimore's fourth- and eighth-graders posted significant gains in reading on a rigorous national exam, but math scores declined and student achievement still lags significantly, according to results released Wednesday.

Baltimore's performance on the National Assessment of Educational Progress provided what city school officials call a "reality check." The results come as the district is starting to teach the Common Core, a new set of tougher standards being implemented in Maryland and 45 other states.

The city was among 21 large urban school districts across the country that participated in the voluntary reporting of scores, called the Trial Urban District Assessment (TUDA), for grades four and eight. The results measure the achievement of districts with primarily low-income and minority student populations every two years.

This year, the Baltimore district scored in the bottom third in all grades and all subjects, performing better than cities such as Cleveland and Detroit, but behind Boston and Washington.

The percentage of eighth-graders reading at proficient levels was 16 percent, but the city noted a 6-point increase in their average reading scores — one of the most significant increases of all the cities. The number of eighth-graders scoring proficient in reading trailed the state by 26 percentage points.

And while average fourth-grade reading scores rose by 4 points from 2011, only 14 percent of those students were considered proficient in reading.

In math, 19 percent of fourth-graders scored proficient this year and 13 percent of eighth-graders did. The comparison to 2011 scores was deemed not statistically significant.

The test is more difficult than state tests, and city students performed much better on the Maryland School Assessments. For example, 70 percent of Baltimore's elementary school students were deemed proficient in reading on the state assessments this year.

Jennifer Bell-Ellwanger, interim chief of staff for the school system, said that while the city posted some gains on the national test over time, the results demonstrate just how much the district needs to prepare for the Common Core assessments.

The Common Core is the largest overhaul of academics to take place in the city in decades. Maryland will begin piloting a new statewide test that is aligned with the Common Core in the spring.

"We're using this as a real baseline now," Bell-Ellwanger said of the national test. "We're hoping that now our schools will be learning more about what it means to be proficient with these new standards, and that we will continue to see improvement over time."

But she said district officials saw progress in the results. For example, she said the eighth-grade reading scores, in particular, were promising because those students outperformed eighth-graders from four years ago, when the city first participated.

National officials called the results "encouraging" and said it was evidence that the district's emphasis on literacy under the Common Core standards was starting to show results. The city has been implementing parts of the new curriculum for several years.

Michael Casserly, executive director of the Council of Great City Schools, called the reading gains among the most "significant and substantial" of any city that participated.

Casserly said that because the national test is similar to the rigor of the Common Core, the city should be encouraged that it is seeing better results where they have put the most effort.

"NAEP scores have always had the same level of rigor that the new assessments are starting to measure," Casserly said. "So this is encouraging."

He said he believes the district's math scores reflect a statewide trend this year, when math scores dropped on the Maryland School Assessments. He said he believes that cities like Washington, where TUDA scores soared in math, had a head start on Common Core reforms in math.

"I'm enormously hopeful that the reading gains will continue and the city will start to see improvements in math achievement," Casserly said.

Bell-Ellwanger said that overall, the district is looking at how the results can help it face the challenges ahead.

"We are cautiously optimistic, and we are not overly cheery," she said. "But I think that in the face of all of the change ... our students held their own, and we're moving in the right direction."

erica.green@baltsun.com

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