More than 150 Alexandria teachers, wearing solemn expressions and black clothing, packed a regular meeting of their city's School Board last night to protest the salaries planned for the next school year.

Angered by the board's refusal to propose a 5 percent minimum pay raise, most of the city's 740 public school teachers have refrained all week from performing any of their normal tasks not required by their contracts.

Members of the Education Association of Alexandria, which represents most teachers, unfurled dozens of long paper banners listing the many volunteer jobs they normally carry out in the course of a day.

"Teachers are in mourning today," said Pamela Walkup, the association's president, in unscheduled remarks to the board. "Each teacher has chosen to express this mourning in his or her own way." she said. "We mourn our lost 1 percent; we mourn our broken promises."

School Superintendent Robert W. Peebles originally proposed that all Alexandria teachers get at least 5 percent raises, but the board cut that figure to 4 percent.

Most board members have said they were certain that the City Council, which must approve the overall school budget, would not allow more than that. The 1 percent difference will save $434,000.

Alexandria teachers have complained that the increase would leave them with a lower minimum salary level than neighboring school systems.

The minimum salary for a new teacher in Alexandria next year will be $18,100, almost $1,000 less than the level in Arlington and Fairfax counties, according to Walkup.

As part of their protest, the EAA will begin next week to send letters to prospective teachers suggesting that they might be happier working elsewhere.

Board Chairman Lou Cook says the 4 percent figure is misleading because 80 percent of the city's teachers will receive raises higher than that in the coming year, based on seniority.

The average increase will be 6.7 percent, according to statistics offered last night by the School Board.

Elsewhere in the Washington area, proposed minimum salary increases are: 4.3 percent in Arlington, 5.7 percent in Fairfax County, 6.5 percent in Montgomery County and 7 percent in Prince George's County, according to the Metropolitan Washington Council of Governments.

Board member Timothy S. Elliott, who was a member of the committee that negotiated with the teachers, suggested that Walkup and Cook meet next week to plan for better communication between the full board and the teachers.