AS A GENERAL principle, school systems can expect resistance whenever parents think that their children are being used to serve other people's purposes. In Arlington County, black parents are now pressing questions about a desegregation plan that imposes the long rides on the black children. In Montgomery County, a group of white parents in Chevy Chase has organized a rebellion against the revival of the Rosemary Hills school pairing plan. In both cases, the purpose of the busing is the decent and proper one of preventing racial segregation of classrooms. But both raise issues of how much busing, of which kids, and under what circumstances.

Unfortunately, the Chevy Chase parents have resorted to tactics that do them no great credit. In their efforts to induce the county to drop their children from the pairing plan, they have signed statements declaring that they will take their children out of the public schools altogether. Any family has an unqualified right to transfer a child to a private school. But to join in a public threat sounds--although perhaps they had not thought of it precisely this way--like a very upper-middle-class assertion of one's income as a means to a kind of political consideration not available to others. It's not a very appealing performance.

But it's also true that friction at Rosemary Hills has been aggravated by several years of highly political quarreling over pairing there, and a series of reversals in public policy that have generated endless uncertainty over things that responsible parents take seriously. The pairing plan, and the previous school board's decision to abandon it, were important in last fall's school board election. Whether the new board should not have gone more gently in reinstituting it is a subject on which people can reasonably disagree. But at this point, the county and the state board of education can only wish the departing children good luck in their private schools.

In both Montgomery and Arlington counties, anxieties over busing are compounded by declining enrollments and the need to keep closing schools, with inevitable disruption of accustomed attendance patterns. But in Arlington it has been the busing plan that remained unchanged over the years, while the county was transformed. Throughout the Washington suburbs, with the arrival of large Hispanic and Asian minorities, the demography has become much more complex since the basic desegregation policies were established more than a decade ago. How much busing is essential now? Segregated schools in ethnically diverse communities remain as offensive today as they were 30 years ago. But school boards working in good faith are increasingly entitled to latitude in weighing the values of racial balance against parents' resistance to long trips for small children.