The 14 high schools the city is trying to close this year posted lower-than-average graduation rates — but they are not all the city’s worst.

Now, teachers union officials are drawing attention to three other high schools approved for closure that posted graduation rate increases two times or more than the city’s overall 2 percent gain. In the Bronx, Christopher Columbus High School’s 4-year graduation rate rose by 5.7 percentage points, to 41.6 percent. Norman Thomas High School, in Manhattan, saw its 4-year rate go from 37 percent to 47.8 percent. Brooklyn’s Paul Robeson High School saw a similar leap, to 50 percent from 40.4 percent last year.

“We knew that we had increased our graduation rate last year by 10 percent and have been saying that since November but no one pays any attention,” said Stefanie Siegel, a Robeson teacher who has been active in protests against the school’s planned closure.

“When our spirits were high after we won the court case last year, we made great gains in a short period of time,” she said.

That court case was the lawsuit the teachers union won to stop the city from closing 19 low-performing schools. Performance boosts at three of the high schools kept them off the chopping block this year. Two of the schools got higher progress report grades, 85 percent of which depend on graduation rates and students’ progress toward graduation. The city said it was confident in a leadership change at the third school.

The schools with oversized gains this year still lag well behind the citywide average 4-year graduation rate of 61 percent. And many of the other schools slated for closure continued to post dismal graduation figures. The Academy for Environmental Science, for example, posted a 41.3 percent 4-year graduation rate for students who entered in 2006. Metropolitan Corporate Academy’s graduation rate was 41.7 percent. And New Day Academy in the Bronx graduated just 27.8 percent of 2006’s ninth-graders on time. This year was the second time the city moved to close all three of those schools.

But just as was the case last year, the schools slated for closure are not the city’s worst when it comes to graduation rates. Other schools posted similar rates, such as Boys and Girls High School in Brooklyn, where just 38.9 percent of students who entered in 2006 graduated four years later. At Bread and Roses High School in Harlem, the graduation rate is 37.2 percent. The city is trying to apply the less aggressive “transformation” model at Bread and Roses, using federal funds to provide extra resources, and hasn’t yet announced any plans to change Boys and Girls, whose principal has said he does not want the federal school improvement funds.

The two transformation schools that GothamSchools and WNYC are following this year, Chelsea Career and Technical Education High School and William E. Grady Career and Technical Education High School, had graduation rates of 48 percent and 42.3 percent, respectively.

Last year, city officials said they use multiple criteria to decide which schools to close but that they would continue to close schools with too-low graduation rates. Schools Chancellor Dennis Walcott repeated that promise at the city’s press conference about the new graduation data yesterday.