Nine-year-old Rachel Smith, deep in concentration, was tapping away on the word processing machine in her father's office at the U.S. Department of Education yesterday while her brother Aaron, 7, watched a printout of Rachel's work sprout from another machine.

Rachel and Aaron are on spring break from the Jewish Day School in Rockville. Their mother Elizabeth, a consultant, had a job interview downtown yesterday morning, so she dropped them off for an hour in the planning and budget office at the education department where their father Manuel works as an economist.

School vacations may be long-awaited treats for youngsters, but they are often high-anxiety times for working parents who must figure out how to keep their children safe and occupied while they are at work.

Pupils in the D.C. public schools and some area private schools are on vacation until Monday. Public schools in Maryland and Virginia were off last week; Virginia pupils returned on Monday and Maryland students on Tuesday.

"Where should I begin--with the cold, the sprained ankle from falling out of a tree or the stomach virus?" said Michele S. Booth, a secretary in the public affairs office at the education department, reviewing the main events so far of her son's spring vacation.

Booth, a proud mother who has decorated a bulletin board in her office with her son Walter's school papers and artwork, said Walter is staying with his grandmother during working hours this week. Walter, 7, a pupil at Sacred Heart School in the Mount Pleasant neighborhood of Northwest, has been calling her at work six or seven times a day, she said.

"Sometimes he calls to tell me jokes," Booth said. Like, "What do you call a worm and an apple?" Answer: "An apple worm."

"He just laughed and laughed at that one," Booth recalled, rolling her eyes.

Booth's colleagues in the public affairs office are quite indulgent about Walter's calls, since some of them have school-age children too. Beverley Blondell, an information specialist in the same office, says she brought her 5-year-old daughter Meredith to work one day last week because Meredith's school, the Falls Church Children's House of Montessori, was out for the week.

Meredith promptly found a rubber hand lying around the office and startled her mother when she snuck up on her while she was on the phone and dropped it down the front of her dress.

"I didn't scream, I was able to keep a little decorum," Blondell recalled, laughing.

"I only took Meredith in for a half a day. I don't think she could have handled it much longer. She ate the candy bar I had brought along for after lunch at 9 o'clock, so that gives you an idea how quickly things deteriorated."

Blondell said she thinks it is good for children to see where their parents work and that her supervisor has been liberal in allowing employes to bring their children "in emergencies and special occasions."

Manuel Smith said certain education department employes, like himself, used to be able to work flexible schedules, which allowed him to arrange to be home on weekdays when his wife had to be out. "That was taken away. The department decided it was not serving the best interests of the agency," Smith said.

Elizabeth Smith said her children's school vacation schedule still is not generally a problem for her since, as a consultant, she can do some of her work at home. But, she said, "For most parents, it's very difficult. You have to take time off from your job. Or you have to send your children to grandparents and relatives."

Some working parents in the Smiths' Chevy Chase neighborhood rely on neighbors who are home all day to watch their children, she added.

Certain federal agencies, like the education department, Department of Labor, Equal Employment Opportunity Commission, Department of Health and Human Services, National Institutes of Health and Department of Housing and Urban Development, allow private day care centers to operate in their buildings for the benefit of their employes.

Many of the city's day care facilities say the number of children they serve ususally increases somewhat over the spring break--but not much, since the centers generally are at or near capacity year round.

City libraries reported an influx of youngsters this week. The Watha T. Daniels Branch serving the Shaw area is offering a special story hour and film every day.

The Anacostia branch has been "just flooded" this week with public school pupils working on research papers and attending the library's special programs, according to head librarian Margaret Kemp.

She said 75 youngsters, more than double the usual number, attended the library's Tuesday afternoon "talk program" this week.

The city recreation department is also sponsoring events this week including kite-making classes every day at the Hillcrest Recreation Center in Southeast, an Easter Egg Hunt Friday at the Oyster Recreation Center in Northwest and a "soccer bowl" Saturday at the Hearst Recreation Center in Northwest.