The Fairfax County School Board selected a vice chairman last night in an unusual party-line vote.

The meeting, the first for three of the 10 board members and for the new superintendent, Robert R. Spillane, also heard strong demands by teachers for a voice in designing a new merit pay program next year.

After reelecting its chairman, Mary Collier, the board picked as its vice chairman Joy Korologos, a Republican at-large member appointed by the current County Board of Supervisors, which is dominated by Republicans.

On a 6-to-3 vote along party lines, Korologos defeated Laura McDowall, a Democrat of the Annandale District who was appointed to the School Board on the nomination of a Democratic supervisor. Democrat Anthony Lane was absent.

Although board offices have previously been contested, such party-line votes have been rare. Since the board's controversial vote last spring to close Fort Hunt High School -- a decision opposed by some top local Republican officials School Board members said political tensions had been heightened.

Several members said they were not aware the vote was along party lines until it was pointed out to them. "I don't know that I read any signals of change in it," McDowall said. Collier said the vote reflected the fact that the board has "strong members and strong choices. There's no rancor over it."

The board heard strong pleas from the Fairfax County Federation of Teachers and the Fairfax Education Association for a stronger voice on a task force and a steering committee overseeing the design of a new merit pay program for teachers. Both teacher associations urged strongly that teacher representatives on those committees not be picked by the school administration.

Spillane said he would consult with the teacher groups, although "that's not to say we'll do it exactly their way."

Several board members said they were disturbed by the underrepresentation of teachers and urged Spillane's staff to remedy that. Collier said afterward the board's message was "that teachers need to be involved."

The board tried an experimental teacher incentive program last year, but there was general agreement it was poorly planned and needed revision. The board voted last night to come up with a new program next year to reward good teachers and encourage them to stay in the school system.