Nearly a year ago, when the Montgomery County school board set about the task of choosing schools to close, worried parents took some comfort from the promise that the decisions would be based on objective factors such as the conditions of school buildings and the numbers of students enrolled.

Board members said their chief motive was financial: With student enrollment declining, about $6 million could be saved if the county did not waste so much money on buildings that were half filled.

But now, with 28 schools slated for closing by 1984 and numerous boundaries redrawn, many parents and some school system staff members are enraged. From Rockville to Bethesda to Silver Spring, some people are scratching their heads in amazement over what they believe are a series of decisions that cannot be supported by the board's own guidelines.

For example, the board voted to keep open a school with one of the smallest enrollments, Rollingwood Elementary, and the one in the worst physical condition, Bradley Elementary. Both were recommended for closing based on data supplied in the superintendent's master plan.

By contrast, the board picked out a relatively large school not originally targeted for closing, Rosemary Hills Elementary, and shut it primarily for "educational" reasons and to enhance "stabilization" in the area, grounds not used in the superintendent's screening process. Rosemary Hills was part of a school pairing established five years ago to improve racial integration.

Such contradictions were also apparent when the board tried to redraw school boundaries.

The board's majority voted to withdraw minority students from the Montgomery Blair High School area to help improve racial balance, but refused to add a significant number of white students. The net result will be no decrease in the percentage of minority students, and a drain of so many students from Blair High that the school may have difficulty in future years providing the variety of courses it now offers.

But when the issue of boundary changes and enrollment came up regarding Cresthaven Elementary, the neighborhood school of board members Marian L. Greenblatt and Eleanor D. Zappone, the end result was quite different. In its efforts to beef up Cresthaven the board improved racial balance at that school but at the same time annexed enough of the neighboring Jackson Road Elementary district to raise the possibility that Jackson Road will be in jeopardy if more closings are necessary in future years.

It was decisions such as these that deviated enough from the superintendent's plan to arouse distrust and bitterness among many parents and to prompt some communities to hire lawyers and plan lawsuits.

Even the board's vice president, Elizabeth Spencer, declared after the final votes were cast last week that she was "ashamed" of the board's "hybrid" solution for shutting buildings and shuttling students.

"One is forced to wonder what hidden agendas may exist," Spencer said. "What seems to have occurred is the selective listening to citizen plaints with the conclusion that this board does not, and can not, represent all the county nor the best interests of all children residing in Montgomery County."

In drawing up a master plan for closing some 30 schools, Superintendent Edward Andrews and the school system staff screened all of the county's 177 schools and rated them on four objective factors: student enrollment, the need for renovation, the size of the school and what percentage was occupied, and the number of upper-level schools into which each lower school fed.

Using these guidelines, only about six schools were clearly identified as ones that should stay open, and roughly the same number were obvious choices for closure. So judgments had to be made in about 25 other cases.

According to Spencer, this is what happened: "In some instances, a single measure seems to be most weighty -- here, it's the existence of an elementary school gym; there it's test scores, as if buildings alone determined the ability to learn; yonder, it's the condition of a building."

One of the first indications that new factors were creeping into the selection process came when the board announced, less than a month after the superintendent's final plan was issued, that 12 additional schools were to be considered as alternatives to the 31 named for closing in Andrews' master plan.

Hearings were hastily called. Parents and civic groups assembled data to argue their cases. But the handwriting was on the wall. Six schools recommended by the board but not Andrews were closed, including Rosemary Hills and Saddlebrook Elementary, an "open classroom" school.

During the month of voting on schools, the board responded to community pressure in several instances. School groupings established for integration purposes were retained in Takoma Park, even though some board members had argued that it was educationally better to split all the school pairings in the county and return to a system where students attend a single school from kindergarten through sixth grade.

Bradley Elementary was kept open in response to charges that the board was doing little to protect day-care centers that operate out of schools in the Bethesda area. But continuing to operate Bradley will force the board to find $2.2 million for renovation, and even then it is not certain the school will be able to accommodate all the children in the immediate area now receiving day care.

In closing Rosemary Hills the board responded to the concerns of some parents from the mostly affluent Chevy Chase community who had lobbied for an end to a school busing plan that sent their children to that school along with many children from lower socio-economic levels. In that case the parents' concerns fit precisely with the philosophies of several board members, who say they oppose school busing and want to preserve the concept of neighborhood schools.

However, neighborhood schools and busing were less important when the board decided to send the mostly white student population from Pine Crest, Forest Knolls, and Four Corners elementaries to Einstein High instead of Blair, even though Blair was closer to most of those students' homes.

One of the most volatile issues arising from the school closings was that of racial balance. Although dissenting board member Blair G. Ewing repeatedly urged the board to look at racial balance as part of its decisions, questions of minority enrollment rarely surfaced in the board's public debates on closings.

When the issue was cited as a factor in decisions, it was generally in connection with elementary school closings. Greenblatt concluded that the board ought to keep open Georgian Forest, Harmony Hills, and Hungerford Park elementaries to avoid disrupting schools with high minority populations. Board member Joseph R. Barse said that expanding Cresthaven's boundary would help "introduce new socio-economic diversity" into the predominantly middle-class, white school.

Earlier in the month, the board's failure to improve the minority balance in the Blair area schools led Ewing to charge that the board had set a pattern in its decisions which could be viewed as discriminatory and subject to legal challenge. He accused the board of "tying a noose" around the Blair school group that would ultimately create the county's "first ghetto."

Spencer, the board vice president, said after the final meeting on closings that the board's decisions "ignore many very serious implications" for racial balance in the schools.

Even the normally quiet, nonvoting student member of the board, Jon Lipson, warned as the board concluded its work that "by not making an active attempt to improve racial balance. . . and by taking actions that may be seen as segregationist, the board is teaching children prejudice and fear and setting a very dangerous example."

Despite the volley of accusations against them, the conservative members of the board say their actions have not been discriminatory. They dismiss the racial issue as media hype and liberal dogma.

Only hours before board members retired with their attorney to review in executive session the racial implications of their actions, board member Suzanne Peyser confidently announced, "We are not isolating anybody racially . . . . Prejudices and fears come from the homes where minority is equated with inferiority, not from elected officials."