Amid some signs that teachers may be trickling back to work, school officials expressed concern yesterday about the effect the six-day-old strike was having on public education in Washington.

"The strike has had a devastating effect on the schools, no doubt about that," said School Superintendent Vincent E. Reed. "We've been nowhere close to having the kind of educational programs we had in schools when our regular teachers were there."

Joyce Jamison, principal of McGogney Elementary School in Southeast Washington, cited important reading and mathematics tests that are coming up in May, saying: "There is no question but that the strike situation will have an impact on some of the students' performances on the tests."

Jamison said the instruction that students are getting now -- with a makeshift staff in most schools of regular teachers, substitutes, administrators and volunteers, including parents -- is by no means on the same level as instruction they receive from regular teachers.

The strike closed out its sixth day yesterday with no signs of movement by either the school board or the striking Washington Teachers' Union. No negotiations were scheduled and union President William Simons said he does not intend to return to the bargaining table unless the board reinstates the expired contract with the teachers.

The union said that 89 percent of the teachers had continued the strike, but that figure was disputed by school officials. Reed said 47 percent of the teachers were back at work yesterday and that 53 percent of the students were also in school.

There was no way to verify any of these figures, but visits to a number of schools scattered around the city showed an increase in the number of teachers who reported to work.

At Friendship Educational Center in Southeast Washington, Principal Larry Paige said 45 of that school's 100 teachers were on duty yesterday. Paige said that 23 of the 45 returned to work yesterday -- one day after D.C. Superior Court Judge Gladys Kessler ruled the union in contempt of court for disobeying her order not to strike and placed heavy fines on the union and union officials.

The union returned to court yesterday to ask that a temporary restraining order be issued to stop Reed from ending automatic union dues deductions on paychecks that will be given to teachers this Friday.

Judge Kessler, who fined the union Monday, denied the request, leaving Reed free not to deduct approximately $30,000 in union dues from the teachers' paychecks.

The checks that teachers will receive this week will be for work completed before March 1. Since the srtike began March 6, striking teachers will not miss a paycheck until the April 1 checks are issued.

At a union rally yesterday at the Greater New Hope Baptist Church, William Simons, president of the teachers' union, told about 1,500 teachers that he knew some teachers were returning to school.

"We know some people went back to school today," Simons said. "We are not going back until the board guarantees us the basic fundamental protection for teachers. That fundamental protection is the contract between the Washington Teachers' Union and the D.C. school board."

Simons said teachers were asking him how long the strike would last and he said there was one answer to that question: "The answer should be, without any equivocation, as long as necessary."

Simons told the teachers that the union was not worried about the fines levied by Judge Kessler. Those fines, which were to be imposed only if the union did not end the strike yesterday, were placed on Simons, union officials and the union.

The judge said the union will be fined $5,000 for the first day that it does not comply with her order against striking and an amount $5,000 larger than the previous day's fine for every subsequent day that the strike continues. Thus, on the second day that the union does not follow the judge's order, it will be fined $10,000; on the third day $15,000, and so on.

Members of the union's executive board will be fined $250 for the first day that they fail to obey the court's order -- in effect, yesterday -- and an amount $250 greater than the amount they were fined the previous day for the duration of the strike.

Simons was fined $500 for the first day that the union continued to violate the court order against striking and amounts $500 larger than the previous day's fine until the strike ends. That means that Simons will be fined $500 for the first day, $1,000 the second day and $1,500 the third day, totaling $3,000 for the first three days.

Individual members of the union were not fined by the judge.

At yesterday's union rally Simons told the teachers he was asking other unions representing clerical staff, janitors and cafeteria workers at schools to join the strike effort. He said he was also calling on transit and sanitation workers to "do a few things that cause inconviences to people in the city."

"This is no longer a teachers' union fight," Simons said. "It is a labor union fight. (Other unions know) that if we go down the drain they may be the next to go."

There was no indication last night that any other unions had agreed to Simons' request for help with the teachers' strike. But the D.C. Fire Fighters' Association issued a satement of support for the teachers.

"We have worked with the teachers on many issues and we know that to survive in this city all employes must stand together. If the Washington teachers are destroyed today it will be the firefighters tomorrow and some other employes the next day. This is not a teacher fight -- it is the fight of every working person."

The union has scheduled a 1 p.m. rally at Greater New Hope Baptist Church for today and a "Washington Teachers' Union Night" at a disco, the Foxtrappe. The D.C. school board has scheduled a briefing on the court action Monday and Tuesday for board members at 1 p.m.

There were no reported incidents of violence on picket lines yesterday. At Terrell Junior High School, First and Pierce streets NW, firemen said two small fires of "suspicious origin" were found burning in fourth-floor classrooms. In one room a fire was burning in a desk and in the other room a fire burned through books on a shelf. In addition, firemen reported, the gas jets in the school cafeteria were turned on.