IN MONTGOMERY COUNTY, the most important choices in Tuesday's election are those for the school board. The schools are the public service that touches families most directly and about which they care most deeply. The board of the past four years has become increasingly strident, disruptive and divisive. Tuesday is the voters' chance to do something about that.

In this nonpartisan election, the primary is a runoff in which the current 15 candidates will be reduced to eight, competing for the four seats to be filled in November. Among those 15, there are more than enough who are capable of restoring the competence and elevation of view that has guided the Montgomery school system through most of its distinguished history. But there are two who deserve to be eliminated early and decisively -- the two incumbents running for reelection, Joseph R. Barse and Carol F. Wallace.

Voters might usefully recall the botch of the past year's school closings. Closing schools is always painful, but the incumbent board managed to turn it into a coarsely ethnic issue of white families versus black and Hispanic families. It is a lamentable departure from Montgomery County's tradition of regard for the rules of civility, not to mention the law. As for the law, the State Board of Education offered its own judgment last spring when, in an unprecedented step, it reversed the Montgomery board's decision on several schools. The county board appealed. This week the court threw the appeal out. No one who has participated in this performance is entitled to remain on the board.

At another point on the ballot, the county's voters will have to deal with the defective Maryland law on the selection of judges. Four judges recently appointed to the circuit court must now run for full 15-year terms. The voters are entitled to a chance to remove a bad appointment, in a yes-or-no vote to confirm it. But the state's present law allows other candidates to run against the judges in office. That's dangerous, because it throws the judges into the politics of a highly partisan election campaign. The sitting judges are at a great disadvantage, since they are forbidden to discuss the law or their work in anything but the vaguest generalities. Nor can they properly raise campaign funds. The pressures of the campaign tend to put them under unfortunate obligations to the parties and the slate-makers.

The remedy, until the law is changed, is to vote for the sitting judges. That's a vote to keep the judges out of campaign politics and out of political debt to party managers. The four sitting judges on the Montgomery ballot, all able lawyers and well qualified to serve on the bench, are Rosalyn B. Bell, James S. McAuliffe Jr., William C. Miller and Irma S. Raker.

As for the many other offices on the ballot, we shall stick to our general rule of refraining from endorsements in party primaries. While we break it in some jurisdictions, like the District of Columbia, where nomination is much the same thing as election, the two-party system is alive and well in Montgomery. But there are several considerations that voters might want to keep in mind. As the school board's misadventures demonstrate, the county is no longer the homogeneous suburban community that some of its residents remember. Running its government is not merely a matter of clean and sharp administration of accepted rules of good government. It will take real political skill to lead the county through the collisions of interest and purpose ahead. Fiscal pressures are likely to keep rising, since real estate values have not only stopped rising but, in some areas, fallen. The county can no longer count on a steadily expanding tax base for automatically rising revenues.

Finally, a minor point but a visible one, the long, rancorous quarrel over the county's department of liquor control is not a serious issue. The various charges of mismanagement and favoritism have been the subject of five official inquiries over the past two years that produced no evidence of wrongdoing. It is wiser to make choices on the conduct, not of the liquor dispensaries, but of the county's fiscal and social policy.