A teacher at Kehillah Schechter Academy asked her students in June to come up with personal anecdotes to illustrate a lesson she had just delivered.

The students, gathered in a mixed-age classroom at the pluralistic day school southwest of Boston, included kindergartners through second-graders.

Spontaneously, the students split themselves into groups and, like workers on an assembly line, divided the labor based on tasks they knew how to perform.

“The kindergarten kids were just learning to write, but the first- and second- graders already knew how to read,” said Nitzan Resnick, one of KSA’s two heads of school. “All of a sudden they broke up in groups. The youngest kids were drawing the pictures for the story, and the older kids were doing all the writing. It was real teamwork.”

Most traditional schools tend to divide students by age. But KSA is among a number of Jewish schools that have migrated to a mixed-age model, which instead groups children by ability.

Advocates for mixed-age classes believe the model, drawn from the Montessori educational philosophy, allows lessons to be tailored to individual needs while creating an open learning environment in which students are encouraged to thrive at their own pace.

Younger children can learn from their older peers, who in turn have the opportunity to teach their younger classmates what they’ve already mastered.

“We’ve found that the mixing ages is a more successful educational model because it’s a realistic look at where children are instead of where they’re supposed to be,” said Amanda Pogany, head of school at the Luria Academy, a Jewish Montessori school in Brooklyn that inspired KSA to adopt the mixed-age model.

Mixed-age classrooms are a core principle of Montessori education, an approach to learning developed in the early 20th century by the Italian physician and educator Maria Montessori.

While many Jewish schools have adopted the approach for its pedagogical value — some 40 Jewish Montessori schools now exist in North America, according to the Jewish Montessori Society — some see the mixed-age model as a way to deal with declining enrollment.

The Lippmann School in Akron, Ohio, has been around for 40 years, and five years ago switched to a mixed-age model for pragmatic reasons — the school just didn’t have enough kids. But it retained the model for its academic and social benefits, and the results have been dramatic.

“We’re now growing since we’ve implemented multi-age classrooms,” said Sam Chestnut, Lippmann’s head of school. “We had 67 students three years ago and next year we’re welcoming 105.

“When you have multi-age classrooms, it forces differentiation, but in a good way. The same kid can be in a math group with older students and in a reading group with younger students. It makes kids aware of their learning strengths and weaknesses and allows for greater growth.”

At Luria, the students study in mixed-age classrooms. At age 9, the school begins preparing the students to transition to more traditional school settings, seating them at desks and administering regular testing.

Shannon Frank, a Luria parent, said her daughter in the past year was one of the older students who transitioned into a role model, giving lessons to many of the younger students.

“Teaching and articulating an activity requires a higher level of mastery and is a huge boost to self-confidence,” Frank said. “In her first year in the classroom, my daughter was one of the more reserved students and hesitated to participate in group discussions. But in her second year, she was a frequent contributor.”

What began as an experiment seven years ago by Luria parents who wanted an intensive Jewish education and a progressive general studies program has grown to 108 students and 20 instructors.

Luria’s success has prompted other Jewish schools to turn to it for help charting their own paths toward alternative learning.

“We had a strong, progressive educational vision based on attaining skills and setting goals before we contacted Luria,” said Resnick, who visited the Brooklyn school two years ago. “But what inspired me there was the independence of their youngest learners. Also with a personalized education, the kids will grow up to be stronger independent learners.”

As many Jewish schools continue to struggle with financial challenges and declining enrollment, mixed-age classrooms are becoming less of an under-the-radar alternative and more of a mainstream choice.

“The multi-age or ability-grouped classroom is no longer a niche idea, and some would say that it is about time,” said Mark Kramer, the executive director of Ravsak, a network of Jewish community day schools. “This model gives schools much-needed flexibility, allowing for both philosophical and pragmatic drivers to inform good outcomes.”

Either way, the mixed-age model is likely to grow, if only because the Jewish Montessori movement is proliferating across the United States.

Shaarei Chinuch, a Jewish Montessori school for children ages 3 to 6, is due to open in a Chicago suburb this fall. Cincinnati Hebrew Day is adding a Montessori track to its traditional day school program. And Yeshiva Netivot Montessori in New Jersey just graduated its first eighth-grade class.

“We truly integrate our classrooms at all levels,” said Debra Kira, head of school at United Orthodox Syn-agogues Goldberg Montessori School in Houston, the oldest Jewish Montessori school in the country still in operation. “Judaics are sewn into the Montessori method for students, cultivating both a greater love for Judaism and for learning.” n