“We are pretty concerned we are approaching a plateau,” said Andrea Silbert, president of the Eos Foundation, a Boston nonprofit that issued the report, titled Ending Hunger in Our Classrooms. “Schools are often resistant to change. But once schools do breakfast in the classroom, they wonder why they waited so long.”

When schools offer breakfast in the classroom, student participation usually soars. Students are able to munch away on a muffin, a piece of fruit, cereal, or other food while getting settled into their morning routine and doing some school work.

By contrast, when breakfast is offered only in a cafeteria before school begins, many students end up missing it because they are running late. That can be a big problem in Boston where school buses can run behind schedule.

And at a time when schools take on many new initiatives without receiving any money from the state or federal governments to pay for them, the breakfast in the classroom programs can generate money for school systems.

That’s because the federal government reimburses schools for each breakfast they serve, often creating enough cash so school systems can replace kitchen equipment, buy new cafeteria furniture, or make other related purchases.

The production costs of breakfasts are generally lower than hot lunches. The meals include such items as milk, fruit, yogurt, cereal, muffins, and sometimes hot items like egg sandwiches or pancakes.

Of the 638 high-poverty schools in the state, only 215 provide breakfast in the classroom. If every school participated and at least 80 percent of the students ate breakfast, the schools could receive $32 million combined in federal reimbursements.

A bill is pending on Beacon Hill that would require high-poverty schools to provide breakfast after the opening bell.

Meanwhile, Eos is pushing for at least an 80 percent participation rate. New Bedford schools became the first district this year to meet that goal, with 82 percent of students eating breakfasts in the classroom. Other districts, such as Springfield, Holyoke, Brockton, and Lowell, are quickly approaching that benchmark.

“I’m delighted we were able to demonstrate such growth,” said Pia Durkin, New Bedford superintendent, but she added, “It’s not about being the best in the Commonwealth, but giving students what they need to be the most successful.”

Steve Zrike, Holyoke superintendent, said that when he worked as a school principal several years ago he was skeptical about the program, worried about the logistics of getting the meals to the classrooms and the mess students could potentially make — including whether it would cause them to act out.

But last year he decided to roll the program out at all K-8 schools, persuaded by the research and experience of other schools.

“It surprised me how smooth it went,” said Zrike, noting many teachers were supportive of the effort. “They know the needs of our students. We are the poorest school district in the state, and we have kids who go hungry at home.”

At the Gomes Elementary School in New Bedford, the number of students eating breakfast has soared since 2015 when the school shifted breakfast time from the cafeteria, where it was served before the opening bell, to the classroom. Monthly breakfast participation at the 600-student school typically exceeds 90 percent.

Principal Ellyn Gallant said the breakfast program has been one of the most effective vehicles in boosting student achievement. Student tardiness and absences have decreased as well as visits to the school nurse, while MCAS scores have gone up.

The report found that in about half of the 33 school systems statewide with high poverty, 50 percent or less of students were eating breakfast in the classroom. Most charter schools and vocational schools with similar demographics had low participation rates.

Keri Rodrigues, founder and chief executive of Massachusetts Parents United, said school systems have no excuse not to offer breakfast in the classroom, noting that the evidence is clear that participation rates rise while schools reap more in federal meal reimbursements.

“We are holding everyone’s feet to the fire. Kids are hungry and they cannot learn.”

Rodrigues said it is disappointing that a school system like Boston where so many students arrive to school hungry is not providing breakfast in all of its classrooms.

“This program is a no-brainer,” she said. “Boston needs to stop dragging its feet and get this done.”

Chang announced during a back-to-school press conference in September that 50 schools would have breakfast in the classroom this year, up from about 20 the previous school year.

But the program expanded only to two additional schools — Trotter Innovation School and Guild Elementary — while the school system created a position this year to look at expanding breakfast in the classroom to other schools next year.

The stalled effort came amid other changes to the school system’s food program that has generated more success. Namely, the school system brought in a new food vendor that is providing fresh lunches to students who previously received frozen dinners and it has been working with another organization to install kitchens and cook fresh meals at schools that were built decades ago without cafeterias.

Chang said the system remains committed to expanding breakfast in the classroom.

“Ultimately, the goal is to make sure kids are eating,” he said.

“They are more prepared physically and mentally (if they eat), and we want them to get high quality food. I’m optimistic we can figure this out.”