PORTLAND — A new report from the Great Schools Partnership, a nonprofit school support organization, says the city’s only expeditionary learning high school provides an environment of “inclusivity, openness, listening and negotiation.”

The organization presented its evaluation of Casco Bay High School, the city’s smallest high school with about 280 students and 20 teachers, to the School Board last week.

The report states that “the school has demonstrated consistently high levels of accomplishment in every dimension, with exemplary performance … in many areas. In our view, such scores would be rare if other high schools were measured by the same standards.”

The report also presented criticisms of the school, including recommendations that CBHS create policies and procedures for staff consistency.

The report calls for improvement in the analysis of student data and improvements in the math program, in response to students receiving poor scores on standardized tests.

The report stated that “the math classes at Casco Bay routinely operate at a lower cognitive level … and provide fewer opportunities for student collaboration than other classes.”

CBHS Principal Derek Pierce said he knows there are still things the school can improve, but that six years after opening, it is moving from the start-up phase to more solid ground.

“It’s gone about as well as I could have hoped,” said Pierce, who opened the school in 2005.

He said one of the biggest challenges for the school was explaining to the community what its mission was and what kinds of students it serves.

“At first we had an existential crisis,” he said. “We were asking, and the public was asking, ‘should we exist?’ I think that’s answered now.”

Pierce cited the past two years, when all of CBHS’s graduates were accepted to college.

“Not all of them went, some did gap years, but they were all accepted,” he said.

Applying to college is part of the CBHS curriculum and is required of all its students.

“We think it’s important kids have options,” Pierce said. “Of all the things to require, (college applications) are pretty relevant.”

The expeditionary learning model means students work on a themed project that utilizes different academic and creative skills. For instance, last year the junior class did an analysis of the BP oil spill in the Gulf of Mexico. They studied the chemicals involved, the ecological impact, the impact on the people of the area, southern blues music, and raised $30,000 to travel to Biloxi, Miss., to interview people in the area.

“It was eye-opening,” said Noah Lupica, a rising CBHS senior. “To be able to go out and create change, it was amazing.”

Lupica said it was a team effort between the teachers and the students to make the projects happen. She said her experience at CBHS, where she has attended since her freshman year, has been great, thanks to the enthusiastic teachers.

“There’s never a dull moment,” she said. “I absolutely love every one of my teachers. Not a lot of high school students can say that.”

Lupica’s younger brother attends Portland High School, which, she said, is better suited to his personality.

“It’s different, but it works with our different learning styles,” she said.

Pierce said the Biloxi project included some of the best curriculum he has ever seen.

“We want kids, a couple times a year, to do work they never thought they could do,” he said.

Despite the success of its students, CBHS has had some growing pains.

The school was unsure how to handle siblings as part of its admission lottery, until a recent clarification. It now gives preference to siblings, but does not guarantee them admission.

“As we grow up, things come up that we didn’t anticipate,” Pierce said.

The school is hoping to expand in the 2012-2013 school year, to 93 students in its freshman and sophomore classes. If the proposal is accepted, it will allow the school to create a senior class teacher team, something it doesn’t currently have.

Right now, teachers teach 75 percent of the time in one grade level, and 25 percent of the time with seniors.

“We have teams for all the grade levels except the seniors,” Pierce said. “We think we can get some economies of scale (by increasing the size of each graduating class).”

Pierce said the school has a wait list of approximately 70 students, which he sees as validation that the expeditionary learning model is becoming more popular.

The school represents the same demographics as the Portland school system, with about 20 percent English language learners.

Pierce said that in a small school, teachers and administrators often recognize other deficiencies students and their parents might not even know they have, and can work with them on improving in those areas.

“Schooling is hard,” he said. “In a small school, though, the more you know kids, the more you know their needs.”

Emily Parkhurst can be reached at 781-3661 ext. 125 or eparkhurst@theforecaster.net. Follow her on Twitter: @emilyparkhurst.