In a closed meeting yesterday, the District of Columbia school board decided to ask the Washington Teachers Union to agree to another extension of its expired contract and to factfinding proceedings within 15 days if necessary to avert a strike, according to persons who attended the meeting.

The board and union have been negotiating under a 90-day extension of the contract that expires Tuesday. Several major issues, including the length of the school day and school year, have not been resolved.

Under the board proposal, the contract would be extended until Feb. 14. In addition, a federal madiator would enter negotiations and, after 15 days, both sides would begin the fact-finding process that would have to conclude within 15 more days. If that does not succeed, binding arbitration could begin if both sides agree to it.

In fact-finding, a third party enters discussions with the disputing sides, determines the merits of each case and recommends an equitable settlement. But the recommendation is not binding. In binding arbitration, both sides agree beforehand to accept the third party's decision.

Union President William Simons could not be reached for comment on the proposal early this morning.

Before the board's meeting yesterday afternoon, the union sent the board a proposal that would extend the teachers' contract on a day-to-day basis and bring a U.S. mediator into the negotiations. Either the board or the union could cancel this interim agreement with 24 hours notice, under the union's proposal.

The board rejected that offer, according to sources, because the board was told by its negotiators yesterday that the teachers' union has been stalling at the bargaining table and would continue to do so without a time limit being set on negotiations.

"They (the school board's negotiators) feel that Mr. Simons is not trying to conduct serious negotiations," said one board member. "And the board thinks the reason is that (Simons) wants to stall until March when he is up for reelection as president of the union and he can ride the strike sentiment back into office."

Persons at the closed meeting also said that the board's negotiators said that Simons has attended only two of the last 10 negotiation sessions, indicating to them that the union president is not intent on a quick settlement.

In addition the negotiators, according to sources, told the board that since talks began after a near-strike in October the board has given the union eight proposals that modified board positions on issues but the union had never given the board any counter-proposals until yesterday.

"Simons is stalling because he needs a victory to rally his troops around him and get himself reelected," said a board member. "The union's position has been to maintain the existing contract and the board is trying to break them down and get back some of the power the union gained in past contract negotiations.

"Even if we bring in a mediator the union has to lose some of what it's got in this contract," the board member reasoned. "So Simons needs a strike, a victory to show he's still strong. The board doesn't expect a damn thing to come of all these proposals. The teachers have one of the best contracts in the contry and they want to keep it."

Simons began laughing when he heard that the board thinks he is stalling as a ploy to get reelected as the head of the union.

"I won't even use the language necessary to respond to that," Simons said. "When you're wrong you go out and find any rationale to excuse yourself and that's what the board is doing."

According to Simons and board president Minnie S. Woodson, negotiations remained deadlocked as of yesterday. The board and union exchanged new proposals on leave and pay policies, teacher training, personnel files, the authority of school advisory committees and the no-strike clause in the contract. Neither side moved to change its stance on several other issues, however.