Why is Acting D.C. School Superintendent James Guines smiling these days? Not because he has been assured of being the next head of the city's school system. Support for his appointment as permanent superintendent has so far failed to materialize.

The reason for the cat-that-swallowed-the-canary look is his recently proven skill as a master choreographer, playing off the political egos of District politicians for the benefit of children in the city's public schools. d

He was faced with a major public school crisis this year and when about 10,000 first, second and third graders flunked basic reading and math, and had to be held back under the city's new midyear promotion plan. At first, there were paltry few raised eyebrows in city hall. p

Then Guines invited Sterling Tucker, the former City Council chairman -- who's acting a lot like a 1982 candidate for mayor -- to be the voluntary director of Operation Rescue, a project to recruit 1,000 volunteer private-sector tutors.

Tucker has said there was no political motive for his coming to the aid of the children. But Tucker's entrance into the education arena -- and the accompanying spotlight of public attention -- also produced Guines' cleverly calculated side effect. It got every politician and his uncle clamoring to be there, too.

Mayor Marion Barry quickly found $1.4 million in the city's summer jobs program to be used to hire tutors for the children. Council member William R. Spaulding (D-Ward 5), chairman of the Committee on Government Operations and former head of the Education Committee, also jumped in, promising to find an experienced tutorial instructor.

Then on Tuesday, Council Chairman Arrington Dixon, another possible candidate for mayor, scheduled a meeting with Guines to discuss, among other things, what he could do to help.

Hilda Mason (Statehood-At-Large), the current Education Committee chairwoman, took the more optimistic view toward the rush to involvement: "The feeling is that if somebody of Sterling Tucker's stature is getting involved, it must be a serious problem."

What remains to be seen is whether the rather sudden onslaught of enthusiasm for getting quickly involved in school matters will translate into real relief again later this year when the mayor and City Council have to give the school board a budget. Guines might not be in the catbird seat then, anyway, since the board is scheduled to choose a new superintendent before the budget battles begin anew in the fall.

But for the time being, Jim Guines is sounding his own fanfare on the success of his tactics. "I know exactly what I'm doing," he trumpeted. "Since they're going to campaign anyway, they might as well campaign around helping the kids. Everybody was running around without an issue. Everybody knows the political motive is there."

Joseph P. Yeldell, former director of the Department of Human Resources, is back in the District Building. But then again, he's not.

Yeldell was once one of the most flamboyant figures in city government, always close to the center of power. With Walter E. Washington as mayor, Yeldell controlled the largest city department and one-third of the city budget, and dispensed patronage to form his own kind of political machine.

He left under the cloud of indictment in 1978, but after a federal jury in Philadelphia found him not guilty of bribery and conspiracy charges a year later, Yeldell returned to city government -- not to his spacious DHR office on the fourth floor, just below the mayor's; not to a perch across the street as the mayor's general assistant, who on at least one occasion ran the cabinet meeting. Instead, Yeldell was tucked away in the city's computer center in the bowels of an abandoned freeway construction site as Massachusetts Avenue and Third Street NW.

At the same time, some of Barry's top aides hoped Yeldell would go away with time. Among many of those who supported Barry, Yeldell was the symbol of the kind of indifference and faulty management that they had hoped to eliminate when Barry replaced Washington as mayor.

But for Barry, there were other factors. For one, Yeldell had a right to be rehired. What's more, the Barry people were not about to risk a personnel fight over someone who had considerable support among some sections of Washington voters where Barry, a mayor interested in broadening his slim base, was close to despised.

Yeldell had been a computer salesman before he became a bureaucrat. And when he came back on the city payroll, he went to SHARE, the D.C. government's underground computer center. There he ended up on the wrong side of a power struggle over the city's faulty and error-fraught computer system. Yeldell backed Francis (Bob) Yates, a 30-year data processing veteran, over Ed Winner, the assistant city administrator for financial management, in a shake-up aimed at ending the constant breakdowns and errors that have hampered the city's bookkeeping.

After the battle, he was kicked upstairs. Now Yeldell is back on the fifth floor of the District Building, in City Administrator Elijah B. Roger's office suite as an official adviser on computer systems and data processing.

He no longer dominates headlines with his pronouncements. His car no longer has the prestigious No. 11 license plate. His appearance in the corridors of the District Building is no longer as electrifying. In fact, he is rarely seen, and when someone does approach him, he is always soft-spoken.

Joe Yeldell has returned to city hall in perhaps the most ironic circumstances -- he's back on top, without the power.