The Alexandria School Board approved a 7.8 percent increase in Teachers' salaries and benefits last night that is close to what the teachers' organization had demanded.

The organization - the Education Association of Alexandria - had threatened a "work-to-the-rule" job action if the demand for an 8 percent increase were not met.

The organization, which represents 735 of the city's 840 teachers, is still scheduled to decide tonight whether to begin the slowdown in protest.

Val Martin, president of the group, remarked following the unanimous school board vote: "with the budget the City Council gave us, this is the best we could do." She called the increase "a compromise" and "far from perfect."

Earlier this year, the council approved a $34 million budget for the school system, which included $1.7 million for teacher and other school staff salary increases.

Under the approved package proposed by school Superintendent John C. Bristol, the teachers will receive a 2.6 percent raise based on each year of school service, as well as a 4.7 percent raise above their current salaries. Most teachers will also receive a 0.5 percent increase in health insurance benefits.

The effect of the salary and benefits increase means that a teacher making $17,000 per year - the average salary for Alexandria teachers - will get a $1,241 raise. Salaries for teachers range from $11,000 to $27,000 depending upon academic degrees and seniority, Martin said.

The nine-member school board also approved last night a number of changes in the school system's policies regulating the authority of administrators over teachers. According to Martin, some of these changes carry enormous "emotional significance" for teachers.

In one of the most hotly debated personnel issues, the board stated that a teacher who declines to perform certain extra curricular tasks, such as coaching or directing school newspapers, will not be penalized in terms of his regular salary or job position.

In recent months, the teachers' group has called for Superintendent Bristol's resignation, staged demonstrations and threatened a "work-to-the-rule" job action similar to ones staged or threatened this year by teacher organizations in Fairfax, Arlington, Loudoun and Prince George's counties.