Public schools in the District of Columbia will be open today despite a strike by the Washington Teachers Union that began at 12:01 this morning in the face of a temporary restraining order barring a walkout.

Schools superintendent Vincent E. Reed said schools would be kept open by using administrative staff, substitute teachers and retired teachers in classrooms. Reed said he met yesterday with Mayor Marion Barry and some school board members, and that Barry assured school officials that police would protect all teachers who want to report to work today.

The restraining order, barring the union from striking for 10 days, was by D.C. Superior Court Judge Gladys Kessler at 10:45 last night, about an hour after a union rally disbanded with union officials promising to close schools "100 percen" today.

Judge Kessler issued the order at the request of the school board and cited as her reasons for doing so the "irreparable" harm that would be done by a strike and the fact that teachers had signed affidavits agreeing not to strike when they were hired.

Reached at teachers' union headquarters minutes after the strike deadline had passed, union president William Simons' told a reporter, "... the strike is on; I don't think there'll be much school today."

Simons, who appeared with school officials at a hearing before Judge Kessler prior to issuance of the restraining order, said, "I have no idea whatsoever how the teachers will react [to the order]. I don't want to be held in contempt of court, but we will have to see."

At the union's headquarters, union officials were advising teachers by phone that the strike was on as scheduled, despite the judge's order.

"We got one of those temporary restraining orders last time and it didn't mean anything," said William Stewart, a member of the union's executive board. "We'll be on strike in the morning."

"We are ignoring the order," said Simons' assistant Harold Fisher.

Just after midnight union pickets were stationed at a number of city schools in an effort to persuade overnight custodial personnel not to enter the buildings.

At last night's pre-strike rally, Fisher, told about 2,500 teachers that picket lines would be set up at all schools at 6 a.m.

Reed said yesterday that with or without a strike, "We plan to have classes and go ahead with a full educational program. Parents should send their children to school at the regular time... we are taking steps to protect people who want to pass through picket lines. We are honoring the rights of the teachers who want to be on the picket lines, and I hope that people on the lines will honor the rights of teachers who want to come to work."

The last teacher's strike here, in 1972, lasted 2 1/2 weeks and also was conducted in defiance of a temporary restraining order.

About 5,000 of the D.C. school system's 6,000 teachers are members of the union.

Reed said teachers who participate in the strike could be fined or lose their jobs because the strike is illegal under the U.S. code. Reed said he did not know if other unions, such as the cafeteria workers, would honor the teachers' picket lines.

Shirley O. Brown, head of the Council of School Officers, which includes school principals, said yesterday his union will not honor picket lines and principals will open schools as usual.Brown said principals have been instructed to request permission to close schools if there are not enough teachers or administrative persounnel present to control students and to safely run the school.

However, Geraldine Boykin, executive director of Council 20 of the American Federation of State County and Muncipal Employes, said her union members, including cafeteria workers, secretaries and clerical workers, will not perform teaching duties and will not croww picket lines if they are threatened by strikers.

"It is up to our individual members to do what they think is right," Boykin said.

Boykin said she hopes Reed is not including cafeteria workers and other nonteaching school personnel among the staff that he is counting on to operate schools tomorrow. She said that would be a violation of their contract.

Reed sent notices yesterday to all school administrators, including those who do not usually work in schools, ordering them to go to regional school headquarters this morning, where they will be assigned to schools that need teaching staff.

The school system also has notified administrators, many of whom are former teachers and union members, that no administrative leave will be granted during the strike.

Meanwhile, teachers have been preparing for the strike, which was called Sunday by the union's executive committee. Union representatives at every school building have polled teachers to see who many will go out and how long they are willing to stay out. In addition, the teachers who said they would not strike were asked if they would honor a picket line.

"The teachers are really ready to go out on this one," said Dan Maloney, a teacher at Seaton Elementary School in Northwest Washington.

"Everyone feels like we have a very good reason this time with the board trying to infringe on all the little rights that teachers have gained in the past and make schools into a dictatorship of administrators. Plus, we don't have a contract and people don't want to work without a contract. Administrators could tell you to do anything."

Maloney said the teachers are particularly upset by three board negotiating proposals. One would increase the length of the teachers' work day, while another would lengthen the school year. In neither case would teachers be given additional compensation.

In addition, the board has sought in bargaining sessions to lessen the amount of influence that teachers and the union have in determining "school policy," such as what duties teachers will perform, and whether teachers or school administrators shall have final responsibility for determining students' grades.

Union officials have highlighted the same issues in recent meetings with their members, saying that the teachers would be taking a 33 percent pay cut if they agreed to work the longer hours and days without a pay increase.

The school board's negotiations with the teachers' union are limited to the terms of working conditions and fringe benefits for teachers. The City Council and Congress set the pay scale for teachers.

Board members, who have been strongly criticized by parents and politicians about the quality of city schools, have said that during the current negotiations they are seeking to regain concessions made to the union by prior school boards.

With greater authority and increased ability to control what goes on in the classroom, board members have said they would be able to improve schools. A key to increased authority, according to the board, would be putting an end to allowing teachers and the union to influence the shaping of educational policy.

Under the board's proposals the teachers would have to work 200 school days instead of the 186 days they work under the old contract. In addition the teachers' school day would be lengthened from six hours with one-hour lunch period to a seven-hour day with a one-hour lunch period.

The board's proposals also would require teachers to attend parent-teachers meetings at the discretion of administrators and reduce the authority of the School Chapter Advisory Committees, teachers' groups that in the past have acted to challenge principals on the way individual schools are run.

One major union proposal at issue would shorten the procedure under which teachers may complain about administrators.

The union also is seeking to have a teacher guaranteed the right to transfer to another school.

Much of the disagreement between the board and the union stems from a 1971 contract agreement in which the board promised to support a pay raise for teachers if they would agree to work longer hours when the wage increase was granted by the City Council.

The teachers were granted the raise but the union said the added money was insufficient and had refused to agree to increased workload.

The current, strike threat comes more than a year after the last teachers' contract expired in January 1978. Since then the board has extended the contract three times. The board refused a fourth extension on Feb. 14, arguing that the union was stalling the talks because they were happy with the old contract and were pleased to have the old contract continued again and again.

"I hope parents will stick with us," said Minnie S. Woodson, school board president. "The board has the education of the children and their needs in mind at all times. That is our position."