In more than three hours of intense questioning last night, members of the Cambridge School Committee pressed school district officials for more details on the proposed merger of two elementary schools.

Superintendent of Schools Bobbie J. D'Alessandro presented a 60-page proposal for the union of the Fletcher and Maynard schools yesterday. The proposal elaborated on skeleton recommendations she made at a committee meeting three weeks ago.

The plan recommends capping class size at 17 students at the schools, and would exempt the school from the district's system of racial quotas.

The school committee plans to vote next Tuesday on the merger, which would take effect this fall.

But parents who spoke before the school committee last night said they were concerned the plan would result in students moving three times in three years.

"How will displacing them and turning them into nomads help them?" said Chemi Whitlow, a Maynard parent on the steering committee of district officials, teachers and parents which suggested most of the recommendations D'Alessandro gave to the school committee last night.

Under D'Alessandro's plan, she will pick the final location by mid-April. Based on an architectural study currently underway, she will suggest either renovating the Fletcher or Maynard or building a new school--renovations or construction could cost as much as $12 to $15 million.

In the two or three years district officials say it would take to renovate or build a facility, students would temporarily relocate to either the Fletcher or Maynard buildings.