ROCKPORT, Maine — Test scores are in and a boys-only classroom here saw significant learning gains.

“It’s a lot of growth,” said Theresa Lash, principal of Camden-Rockport Elementary School during a presentation on the experimental classroom to the school board Wednesday night.

The ACLU of Maine, meanwhile, which is working to shut down single-gender classrooms in the state, discounts the one-year academic gains and argues that such segregation is unconstitutional and perpetuates gender stereotypes.

On Wednesday, Lash pulled out a sheet of test scores that showed the 18 boys who elected to be in the single-gender class matched their peers’ reading test scores this year. The entire school’s third grade has 61 percent of students meeting the reading standard. The difference is that the students in mixed-gender classrooms scored a 58 percent achievement rate on the exam last year and the boys scored a 33. This means the boys improved by 28 percentage points and their peers only improved by three points.

In math the entire third grade jumped up by 16 percentage points. The boys class went from 56 percent of the students meeting the basic math standard to 72 percent. Their peers in the school improved from 42 to 58 percent in the last year.

“The feedback we’re getting from a variety of tests is that these boys are doing better in school,” Lash said to the school board. “When you look at anecdotal data from the students and parents it’s an overwhelmingly positive response.”

The small school tried a single-gender classroom when it realized that two-thirds of the third-graders would be boys. By separating out a third of the boys, it made the other two third-grade rooms evenly sexed. It also helped engage boys who may have been discouraged with school, the boys’ teacher said Wednesday night after the meeting.

A survey of parents who elected their boys to be in the male-only class all said that their boys had a successful school year.

“He wants to go to school every day. That is a success in itself. I think he’s more willing to take risks, get an answer wrong, and make mistakes while learning,” one parent wrote.

Curiously, when asked if they would enroll their boys in a single-gender class again, only a third of the parents said yes.

“It was worth doing — it did what we wanted to do, to make these boys more engaged in their education. It served its purpose, but there is no reason to continue it at this time. We don’t have the same needs next year,” Lash said at the meeting.

The school lost some of its male enrollment this year, according to assistant superintendent Elaine Nutter. Instead of separating out some boys, the school will try a new model of “team teaching” the fourth grade. Fourth-grade teachers will closely collaborate to share curriculums.

The boys’ teacher, Steve Seidell, agreed that the class served its purpose and the 18 boys he taught are ready to enter a gender-mixed environment again.

“I believe in mixed-gender classrooms but in this case the number of boys played a significant role on the tone of the classroom. It was about this group,” Seidell said, stressing the word “this.”

The group of boys chosen were developmentally lagging, but caught up to speed this year, he said.

“We wanted to give the boys a positive educational experience. Make them buy into school. They did,” Seidell said. “We did this to benefit all the kids. It helped everyone significantly. We think we got the boys on the right track now. Developmentally they were behind and they have come a long way.”

And the boys seemed happy about their time. In a survey of the boys, almost all of them said they’d like to be in a boys-only class again. The boys rated how they did this year on a scale of one to 10 — 10 being the best year of school ever — and the average was a nine.

When asked what they liked best, the boys said they were with their friends this year and “everyone liked the same things I did” and that games were geared to boys. The school also asked how this year was different than any other school year; the boys said there were no girls and it was the loudest class ever.

“I spent a lot of time developing experiential learning activities,” Seidell explained.

Those hands-on — and sometimes loud — activities included digging up “artifacts” that had been planted by the teacher from dirt near the school.

“We did things that would engage the boys and help them with their academics,” he said.

Seidell said he expects to reuse much of the curriculum next year in his mixed-gender third grade class.

Single-gender classrooms have their critics. This week, Sanford school district shut down its single-gender classroom after the American Civil Liberties Union of Maine sent it a letter threatening litigation. The ACLU of Maine believes classroom gender segregation is unconstitutional and perpetuates gender stereotypes, according to the organization’s executive director, Shenna Bellows.

Bellows said the reason the ACLU of Maine sent a letter to Sanford schools but not to the Rockport school was because it had not been aware that there was a boys-only class in the midcoast.

“We haven’t had time to investigate the situation in Rockport, but what we know from the media report is concerning. The idea girls can’t be active and the ‘normal boys’ can’t be quiet can be damaging. Children have the right to be educated based on their needs as individuals not their sex,” Bellows said. “Schools play a role in how students view themselves and others.”

Bellows also doubted that the school’s test results that showed the boys improved in math and reading actually meant much.

“You can’t take a single year and draw definitive conclusions and draw conclusions of single-sex education,” she said. “You have to look across the board and what researchers are finding is that these programs are not increasing academic performance.”

The ACLU of Maine contacted the school on Wednesday and began asking questions about the boys-only classroom, according to Lash.