At first the house had a pool and a tennis court and a full gym, but then the gym was a bit much. So Jemmel Dunn, who is 17 and in charge of these things, took it out.

She kept the pool, though, with her astrological sign (Sagitarius) inlaid in the tile in the bottom. And she said, waving her arm grandly over the plot plan for her house, "I'm going to have me a big weeping willow tree. I love willow trees. I like to see them when the wind blows."

Jemmel Dunn spends most of her afternoons this way, homing her dreams into a careful practice plans that she hopes will make her an architect someday. In the mornings she is a junior at Woodson High School in Northeast Washington, but a 1 p.m. a school bus hauls her out to the big brick Northeast building called the Lemuel A. Penn Career Development Center. She settles in at a drafting table, brandishes compass and T-square, and - like the 400 other District high school students who spent half days at the Penn Center - gets a taste of the working world.

There are printing presses, movie cameras, bindery machines and computer terminals in this airy four-story barn of a building. the students come hopping into class with cameras slung over their shoulders and graphics portfolios under their arms, their heads full of blueprints and fragmented poetry.

They work to the clatter of machinery and the thump of WOL soul, and by the time they have wound up this academic year, they will have produce two 16mm, twelve films, 8mm films, six issues of an all-city newspaper, one bound collection of children's stories, two issues of a glossy city magazine, two literary magazines, one photography magazine, one graphics-adorned calendar and an array of posters, pamphlets, architectural models and mounted black and white photographs.

The late Lemuel Penn might be surprises at what is going on in his name today.

Penn, who was shot to death in 1964 by a sniper in Georgia, had presided over adult and vocational education in the D.C. schools. He was widely respected both as a teacher and an administrator. But that was 13 years ago, a very different era in D.C. school administration. Today the scope and promise of the Penn Center symbolize a new kind of vision for public school students in Washington.

"It's really progressed beyond my personal expectations," said George Gordon, the Penn Center's principal, who came to the school for its opening in 1974. The brick building on 3d Street NE, near McKinley High School, had been used as an office and printing facility for the National Geographic until the school system took it over that fall. Students and teachers cleaned, painted and rearranged the old building, and with a start-up enrollment of vocational classes from other schools, plus the "1310" program then publishing a high school literary magazine at 1310 Vermont Ave. NW, the Penn Center got under way.

From the beginning, its courses have flouted tradition. An urban journalism workshop combines classes in reporting, photojournalism, government and urban studies, television news and radio broadcasting. A literary arts program teaches filmmaking, poetry, photography, fiction and graphic design. The printers tackle computerized IBM typesetters, or convert copy into offset printingplates, or learned the collating and padding and stitching that a bindery worker must know.

What comes out of these programs are students who know how it feels to produce. Edward Bell, a 16-year-old sophomore at McKinley, knows that the intricate, cross-shaped design on what will eventually be stationery and business cards worked itself together in his imagination after a library book showed him the checkered diamonds of the Ivory Coast Baule tribe, and the sunburst star of the Senufo tribe. Edward Bell wants to be a commercial artist, and believes he will make it. "As long as I know the basic," he said. and he does.

Brian McKissick, a 17-year-old McKinley junior, wants to be an advertising artist someday and has already seen his work on print. "Little robots," he described his drawings, smiling. He and three other students a worked up a newspaper advertisemant for a private company and got paid.McKissick will begin hunting for a part-time job when the next school year gets under way, as part of his program. "You get your check and you come here and get your grades." he said, almost in awe.

There are high school juniors at the Penn Center already so accustomed to being reporters themselves that they wince a little when they are questioned, saying it feels odd to be on the other end of an interview. They are pushing deadline now, working up stories on teen-age parents, on youth unemployment, on the special problems of the Asian elderly in Washington. They share dilemmas: "I can't talk to the teen-age fathers; they don't want to be interviewed." "I can't get into a day care center to take pictures inside." Suggestions are offered, help exchanged. They take up cameras and notebooks and go out to try again.

When the Penn students graduated from their respective high schools, according to Penn Center follow-up studies, about 80 per cent are being placed in jobs in areas for which they were trained. Maxine Rosborough, the architectural drawing teacher who presides over evolving house dreams like Jemmel Dunn's, said six of her students now have part-time drafting jobs as part of their school program. She expects that those will turned into summer jobs - "all of the kids who worked part-time last year went right into summer jobs," she said. And from there, Rosborough observed, it is an easy step into what most other graduates find to be a forbidding job market.

Getting into the Penn Center is not quite so easy. The school is recruiting this week, visiting D.C. schools to explain the programs and course offerings, and interested students must have interviews with prospective teachers before being accepted. Once they're in, they have to care about themselves and the work they do - or the Penn Center dumps them.

But the reward at the end is work that matters, work that catches the spirit of an imaginative high school senior. And as one future architect observe last week from his Penn Center drafting table, "If you get a boring job and you don't like to deal with it, it really messes you up."