The Fairfax County School Board voted last night to adopt an experimental teacher evaluation program over the objections of the county PTA, teacher associations and some civic groups.

The program would begin next year in eight county schools -- two high schools, two intermediate and four elementary -- and cost $198,000.

Teachers would be rated every three years on a five-point evaluation scale as exemplary, skillful, competent, marginal or ineffective. Those earning high marks could advance from entry level to so-called Career Level I, then eventually to Career Level II.

Marginal teachers would be eligible for counseling or further training and could be dismissed if those efforts did not help.

Teachers would be evaluated by a team that included other teachers, but the final rating would be up to the school principal.

Teacher pay -- for the moment -- would not be tied to the performance rating, but some believe it eventually may be. School system officials say they believe teachers who receive good rankings will be rewarded with prestige and eligibility to participate in special programs.

Supporters of the plan said it is vital as an opening move to reward good teachers, root out bad ones and encourage pride and professionalism in teaching.

School Superintendent Robert R. Spillane called the plan "in some ways untested, uncharted waters," but said the program could be changed.

School Board Chairman Mary E. Collier said the plan's goal "is to ensure high quality education in the classroom. We're moving tentatively and carefully, but we're moving."

But opponents, although saying teacher evaluation is needed, cited a variety of reasons for changing the plan or postponing its implementation.

Representatives of the county Council of PTAs and the local chapter of the American Association of University Women said the plan was too hastily assembled and vaguely worded. The League of Women Voters has voiced similar concerns.

County PTA President Kevin Bell also said it is too soon to set up a teacher reward system even as a superintendent's commission is studying ways of improving the teaching profession.

The vice president of the Fairfax County Federation of Teachers, Bob Wood, told the board the plan would vest "total evaluative power in the hands of a few principals," and urged more of a voice for teachers.

Donna Caudill, president of the Fairfax Education Association, said that the rating criteria were too vague and that the peer review would hurt morale.