Students and others marched in Rockville in 2014 in support of closing the achievement gap in Montgomery County. (Sarah L. Voisin/The Washington Post)

SOMETHING REMARKABLE is happening in Montgomery County. The biggest and most politically powerful union, which represents some 12,000 public school teachers, is positioning itself as a responsible partner rather than an antagonist in its dealings with local elected officials.

If it continues, the shift will represent an evolution in the political culture of one of the region’s biggest and most diverse localities — a traditionally labor-friendly jurisdiction of 1 million people where profound demographic change is driving a rethinking of settled assumptions.

Among those assumptions is the idea that the teachers union could intimidate politicians to the extent that it would dun candidates for public office for campaign contributions — yes, you read that right — an upside-down practice unknown in the rest of the United States. A correlate of that assumption in recent years has been that in the union’s worldview, compromise was a zero-sum game.

Union officials representing teachers and other school employees are engaged in talks with the county’s Board of Education over previously signed contracts. Remarkably, the union has agreed to repurpose some funds previously earmarked for large wage increases; instead of 8 percent pay hikes in the coming year, most teachers would receive a still-generous 4.5 percent raise. The schools would use the freed-up funds to hire additional staff and reduce class sizes, which have crept higher since the recession.

The union’s concession came with prodding from the County Council, which demanded it in return for increasing school funding beyond the state-mandated formula. Union officials were also mindful that under state law, the Board of Education could have — and would have — imposed the concession had it not been offered.

For students, the deal’s benefits will accrue quickly in terms of enriched educational programs and smaller class sizes, especially in poor and heavily minority schools. In an elementary school with a large component of low-income children, class sizes in the third grade would shrink to 26 kids from 28. Smaller class sizes, it is hoped, will help shrink the achievement gap that bedevils a school system, one of the nation’s 20 largest, in which a majority of students are minorities.

The question now is how the union concessions will be received by 34,000 county employees, two-thirds of whom work in the schools. There are rumblings of dissent from some teachers and principals, though they are generally better-paid than their counterparts in nearby suburban systems.

One idea is to put the agreement to a vote of rank-and-file members. That would be largely symbolic because the deal, once approved by the Board of Education, could not be undone. Still, it would provide a measure of whether teachers are on board with what their leaders and county officials are selling as a new partnership.

Let’s hope they are. Like private-sector workers, teachers and other public employees saw wages stagnate during the recession. Since then, pay for most has grown much faster than that of federal or state employees, to say nothing of wages in most companies.

That’s good; teachers are key to the success of children and the community. It’s also good if, for the sake of better educational outcomes, they’re willing to accept a healthy wage hike rather than an supersized one.