Enrollment in Cambridge public schools has dropped more than 10 percent over the past five years and, according to district projections, the system will lose hundreds more students over the next five years. The mergers would eliminate many of these empty seats.

Consolidation would produce 12 schools, each with between 300 and 500 students and each housed in its own building (currently, several schools share buildings).

But critics say such an aggressive plan threatens a long Cambridge tradition of elementary schools developing their own academic programs. Parents say the educational philosophies of their children’s schools have become a subject of pride and worry that moving students to other schools will be disruptive.

Parents also object to the way administrators have developed and proposed the merger plans, saying the process has been too secretive.

D’Alessandro has told parents that she is considering six options for consolidation—each involving different combinations of schools—but she has kept those plans under wraps.

Over the coming days, she will consult with school committee members, pick one of the six plans and announce it publicly. But parents say they want to see all six options and weigh in beforehand.

“On the surface it seems like it’s open, but underneath it seems really discombobulated,” says Longfellow School parent Greg A. Smutny.

In response to attacks on the process at Monday’s meeting, D’Alessandro assured parents they could offer their opinions on the plan through public hearings in October and November.

“We have to do this together,” she said. “We will be sure that when we go forward, it’s not my plan.”

Last spring, D’Alessandro proposed a consolidation plan for merging several elementary schools and creating middle schools. But she withdrew it when parents—and even committee members—protested that the plan had taken them by surprise.

Despite her reassurances this fall, school committee member Alan C. Price says he worries the process could still rile parents.

“You don’t want to divide the community through the process,” he says.

Skeptics on the school committee also worry that merging so many schools at one time would deal a lethal blow to the city’s precarious controlled choice plan, a system that lets parents choose where their children go to school so long as diversity at each school stays within a set of racial and socioeconomic quotas.

The system is already strained because schools with successful academic programs have long waiting lists, while other schools have half-empty classrooms.

D’Alessandro contends that consolidation will promote a more equitable distribution of resources among all elementary schools and attract parents to historically unpopular schools. That would relieve the pressure on the most popular schools, she says.