They haven't exactly campaigned together, but around Montgomery County, three of the eight Board of Education candidates in Tuesday's elections are being called the "rainbow slate."

With four seats up for election, the "slate" represents an unprecedented chance for minority group members to join a board whose present membership is exclusively white. And, although they don't talk much about it, the three candidates acknowledge that their candidacies have heavy symbolic meaning.

At-large candidate Alan Cheung is the first Asian American to seek election to the board. His campaign has raised $17,000, more than any other candidate, largely through contributions from the Asian community.

Ana Sol Gutierrez, a District 3 candidate, would be the first Hispanic school board member in Maryland.

And Donald R. Buckner, in District 5, would restore a black member to the board after several years' absence.

Traditionally, school board races have revolved around themes of school quality, not ethnic politics. "It is different from any campaign I have seen in all the years I have been involved in Montgomery County -- unequivocally," said Sharon DiFonzo, a longtime resident and school board member since 1984, who is not up for election this year.

Minority enrollment in Montgomery is surging; racial and ethnic minorities account for 37 percent of the county's 103,000 students this year. "The time has come simply because there is a critical mass of immigrant or ethnic minority students," said Gutierrez, 48.

She and others predict that this year's races also may be a harbinger of political change in Montgomery, where a school board stint can be a precursor to other elective offices.

Regardless of who wins, the board will see its greatest turnover in a dozen years. James E. Cronin is the only incumbent among the eight candidates.

And the center of gravity on the board could swing toward its senior and most outspoken member, Blair Ewing, who is helping several novice candidates this year. Ewing has been in the minority on many issues during the last few years, including the 1987 selection of Superindent Harry Pitt, who must to decide this winter whether he wants to retire when his contract expires in July.

The new board also "is going to have to come to terms real quick with a fiscal environment school boards in Montgomery County are not used to having to deal with," said William Beane, a District 1 candidate. The school system is facing uncertain outcomes on several tax referendums Tuesday, potential renegotiation of a teacher contract and pressure elsewhere in Maryland to redistribute state school aid to help poorer jurisdictions.

The races are viewed as close, and relations among some candidates have been testy. There have been allegations, rare in the relatively clean world of Montgomery education politics, of dirty tricks.

This week, the president of the county's PTA council complained that a long-standing advocacy group, EDPAC, has mailed letters erroneously indicating that the PTA agreed with its candidate endorsements. "It was done without my permission, and I do not like being used," said Jean Mallon, the PTA council's president

All county voters may cast ballots in each district race.

In District 1, both Beane and opponent Carol Fanconi are making their first runs for elective office. Beane, 52, is a program analyst for the Army who lives in Gaithersburg and has three children in the school system.

Fanconi, 48, of Laytonsville, is an administrator in the county's Department of Children and Youth who has been active in promoting more facilities and programs in upper county schools.

In District 3, Gutierrez, an aerospace engineer from Chevy Chase, is running against Vicki Rafel, 51, of Chevy Chase, a former president of the county's PTA council who was appointed to the school board for several months in 1988 to replace a member who was ill.

In District 5, Frances Brenneman, 39, of Olney, is a part-time reading teacher at Montgomery College who has two children in the school system and has been active in local PTAs. She is opposed by Buckner, 58, of Colesville, a health professions educator who works as an administrator at the National Library of Medicine.

In the at-large race, Cheung, 53, of Rockville, is a Hong Kong native who works as an administrator in the Department of Veterans Affairs. Cronin, 49, of Silver Spring, has been the school board's president twice during his eight-year tenure.