Fairfax County School Superintendent Daniel A. Domenech has modified his proposal to evaluate all county teachers annually and instead has offered a plan to evaluate experienced teachers once every three years instead of the current five.

Under a proposal presented to the School Board last week, the more frequent evaluations would be phased in beginning this fall, with experienced teachers--those who are past their probation period--moving to a four-year evaluation cycle. The following year, experienced teachers would be evaluated once every three years. New teachers--those with three or fewer years of experience--would continue to be evaluated annually for their first three years.

"Ideally, we'd like to see it done annually, but given the nature of the system that would be difficult," Domenech said. "Three years is a good compromise."

A task force of teachers and administrators will be formed to study the proposal and recommend other possible changes to the system. Those recommendations will then be presented to the community for review before going to the School Board for final approval later this year.

The head of the county's largest teachers union said he doesn't see any need for the changes.

John Butterfield, president of the Fairfax Education Association, said he agrees new teachers need close scrutiny. But, he said, experienced, qualified teachers don't need to be evaluated any more frequently than they are now.

"We see no reason why the current system needs to be changed," Butterfield said. "The system is working--in fact it's held up as a national model."

Fairfax currently evaluates its experienced teachers less frequently than any other Washington area school district, but its evaluation system is one of the most elaborate in the country.

In September, Domenech announced that he would like to move to a system of annual performance reviews for all county teachers, and he suggested that the current evaluation process could be streamlined to make more frequent evaluations possible.

Evaluations are used primarily to assess teachers' strengths and weaknesses and to identify those who might benefit from additional training and resources. With teachers under increasing pressure to prepare students for new high stakes state achievement tests, it is essential that teachers be evaluated more frequently to ensure that they are up to the task, Domenech said.

But some principals and teachers expressed concerns that the already time-consuming and burdensome evaluation process would become even more so if conducted more frequently. They also worried that compacting the current evaluation process to make it easier to conduct reviews more frequently might make the process too short to be meaningful.

The current evaluation system was adopted in 1986 in conjunction with a new merit pay program for teachers. Although the merit pay plan was killed in 1991, school officials kept the evaluation because they liked its thoroughness.

But changes in state law and the large influx of new teachers over the last few years have meant an increasing amount of administrators' time has been tied up in conducting evaluations. Principals estimate the process takes them about 15 hours a teacher.

In March, the Virginia General Assembly changed state law to require that all teachers new to teaching in Virginia schools--whether novice or experienced--be evaluated in each of their first three years of teaching. Before the change, only novice teachers were required to undergo annual evaluations.

The change in law, combined with the record number of new teachers being hired to meet burgeoning enrollment growth, has caused the number of evaluations to skyrocket, school officials said.

During the 1995-96 school year, Fairfax administrators conducted about 2,300 evaluations. Last year, about 4,042 evaluations were done, and the number is expected to rise to about 5,500 this year, school officials said.