When Northwood High School opened its doors to a crush of 1,350 Montgomery County students in the fall of 1956, it was one of dozens of schools built by an affluent county coping with a student population boom of the '50s and '60s.

Not unlike other schools built during the postwar years, Northwood was a sturdy, rambling building, made of concrete block and cement, stone steps and linoleum. Its students were products of middle-class Silver Spring. White, conservative, smart but not the consistently high achievers from schools such as Bethesda Chevy Chase and Montgomery Blair, they expected to get from Northwood the kind of education the county was known to offer. Simply, the best.

Now, years later, Montgomery students and parents still expect consistent, high-quality instruction from their schools. But at issue today, and fiercely debated for the past four years and again during public hearings last week, is whether Northwood, an aging neighborhood center for book learning, bake sales and basketball games, can meet those expectations.

The Montgomery County Board of Education has voted twice since 1981 to close Northwood. It is reconsidering those votes in light of a surge in its student population that is expected to last through the decade.

The board is expected tonight to vote for one last time on what has become the most controversial part of its school facilities plan for next year.

Over the years, Northwood itself has changed and the debate over its proposed demise has taken many turns. No longer a school of white, middle-class suburbia, Northwood serves a student population of 900 -- 43 percent of them black, Hispanic or Asian.

Once designated for massive renovations that were never carried out, the school has not been modernized like others of comparable age in the system. It looks virtually the same, except for worn hallways and a leaking roof, as the day it opened near a then two-lane University Boulevard in a newly bustling Silver Spring.

Arguments over its closing have focused on a range of issues: from neighborhood needs and student enrollments to crowding at other schools and cost for improvements at Northwood.

At the heart of each debate, according to administrators, teachers and parents who have been through the fight before, is a classic clash over educational ideals.

"What we are dealing with here are values and what one considers is important in education," Superintendent Wilmer S. Cody said last week after listening to hours of testimony. "And I think the diversity and variety of the educational program has to be the final issue."

On each side of the issue are people who define quality of education in different ways. There are those who want a neighborhood school, a relatively small facility with the minimum 1,000 students that could ensure a strong curriculum and help relieve crowding in other schools.

And there are those who oppose the continued use of the school, saying the county would have to spend too much money to teach too few students there.

Along with 27 other schools, Northwood was first slated for closing in 1981 when the school board was attempting to cut costs and cope with declining enrollment. In 1983, the board voted to delay the closing from 1984 to 1985.

This year, seeing systemwide student enrollment projections leaping to 103,000 by 1990, the superintendent urged the board to reconsider its position on Northwood, the last of the 28 schools to be closed.

Cody later decided that, based on varying birth rates and housing growth throughout the county, the board should stick by its decision to close the school. But those administrative delays encouraged Northwood parents and students, who had been fighting the closing with a deliberate, methodical resolve few communities had matched over the years.

Last week, they demonstrated their tenacity when hundreds of cheering Northwood supporters filled the auditorium at Wheaton High School, where hearings were held on the school's fate.

"We decided to keep fighting because the figures kept changing," said Freddie Hodges, the leader of Northwood Community Solidarity, a grass-roots organization of parents, students and community leaders who want to save the school.

"And what has got us through the last year," she said, "is that we began asking questions that no one could answer."

The questions concern enrollment projections and cost figures for renovation. Hodges' group and school planners have buffeted each other with conflicting reports during the past year, debating the cost of improvements needed at Northwood and population projections for that school and nearby Einstein, Blair and Kennedy high schools.

Last week, the two sides were hundreds apart in their estimates of school populations into the next decade and as much as $7 million apart in what they say are necessary renovations at the school.

Northwood's arguments were not heard in a vacuum. What Northwood parents said would be a boon to the education system in Montgomery -- a high school of smaller proportions -- parents who have their children enrolled in high schools located north, south and west of Northwood blasted as "fiscally and educationally irresponsible."

"It is totally unacceptable," said Barbara Cantor, head of a group representing Blair High School parents. "As a plan to keep Northwood open, it underenrolls Einstein and Blair . . . while doing nothing to help overcrowding. Is this quality education?"

Speakers from Einstein High School dug out a six-year-old report from Northwood administrators and school board personnel saying, "There is no question that what is needed at Northwood is a major renovation." And Kennedy High parents told the board that juggling students in order to keep Northwood open had "no sound educational purpose" and would sap students from schools that need a higher enrollment in order to offer upper-level courses.

"Why should [the county] just 'make do' at Northwood?" asked William Wisner, president of Einstein's parent-teachers group, which pointed out that previous boards had made commitments to expanded course offerings and modern facilities for all Montgomery students.

The Montgomery County Board of Education has had two chances to consider the fate of Northwood. Since that time, however, three new members -- Sharon DiFonzo, Peggy Slye and Jeremiah Floyd -- have been elected to the seven-member board. Their votes, like those of their more experienced colleagues, still were undecided at the weekend.

"It will not be a decision with which many will be very happy," said Slye, who noted that her telephone had been ringing incessantly. "People can say, and in fact community members do say, board members are elected to serve interests of the community.

"Well, in this case, we have to serve interests of just one group in the county -- all students in the county.