Casco Bay High School Principal Derek Pierce was named Maine’s Principal of the Year on Monday, honored for growing the 11-year-old school in Portland from a fledgling alternative offering to a thriving institution known for its innovative teaching model and close-knit student community.

“Derek Pierce has been the constant in the development of Casco Bay High School as a national model for expeditionary learning,” said Dick Durost, executive director of the Maine Principals’ Association. “His leadership, as well as the commitment of the students, staff and Portland School Department to provide an alternative educational option, is commendable.”

Durost presented the award to Pierce on behalf of the MPA at a surprise ceremony at Casco Bay High. Students let out cheers and gave Pierce a standing ovation when the news was announced.

“I am feeling overwhelmed by (gratitude),” Pierce said, thanking his family, the “planet’s greatest faculty” and in particular, the school’s students. “You are our greatness,” he told them.

“This is further proof we’re not an alternative or an experiment,” Pierce said of the school’s growth since it opened with 80 students and 11 teachers. “We’re not just here for good, we’re here for great.”

Started in 2005, Casco Bay High follows an expeditionary learning model promoted by Outward Bound that includes an interdisciplinary, project-based curriculum and emphasizes real-world learning experiences. It is the smallest of Portland’s three high schools, with about 400 students, less than half the number at Deering and Portland high schools. Its graduation rate of 86 percent in 2013-14, the most recent year available, was higher than the 78 percent and 79 percent at Portland and Deering, respectively.

Every year, Casco Bay High juniors take part in a one-week, cross-cultural experience that involves service and learning. The students use it as a learning opportunity in advance, do service work during the week, then make multi-platform presentations about the experience afterward. This year students will go to Detroit to help with blight removal in the city and interview residents. In past years they have traveled to West Virginia, Mississippi and New York City.

Acting Portland Superintendent Jeanne Crocker, who nominated Pierce for the MPA award, praised his work at the school. The award, she said, “is another one of those Casco Bay High School accolades that are so, so deserved.”

In a written statement, Mayor Ethan Strimling said that “Derek Pierce is a jewel in Portland. I am beyond pleased that he is being recognized statewide for his excellent work with Portland school kids. We are lucky to have his skills in our community.”

In 2014, Pierce won a $100,000 leadership award from the Nellie Mae Foundation, which he used to fund scholarships and projects at the Portland school. The Larry O’Toole Award honors a school leader or organization in New England for innovative leadership in advancing student-centered learning.

Pierce was formerly the principal at Poland Regional High School, and at Whittier Middle School in California from 2002 to 2005. He also was dean of faculty at Whittier from 1998 to 2002.

Also Monday, the MPA announced that Roger “Ron” Robert Jr., principal at North Berwick Elementary School, was named Maine’s Elementary School Principal of the Year.

Durost, the MPA executive director, said Robert has been particularly successful at North Berwick Elementary in involving parents, creating a positive climate at the school and helping struggling students. He has been principal there since 2002, and previously was principal at Hollis Elementary and Hollis Consolidated School and principal of Eliza Libby School in Buxton from 1998 to 2002.

“Ron Robert has been a successful principal for almost 18 years,” Durost said Monday. “His leadership in the ‘100 Days of Giving’ program, the development of daily common planning time for teachers, and the creation of a ‘professional development road map’ are all examples of what makes Principal Robert and the North Berwick Elementary School unique.”

Pierce and Robert will be honored at the MPA’s annual awards banquet April 28.