Washington area schools are closed again today, many exhausting the supply of snow days built into their calendars and forcing administrators to decide how to make up for lost time.

In an attempt to salvage a complete 180-day school year, school officials are considering canceling teacher-training days, dipping into spring break and extending the school year. Fairfax, taking its sixth snow day today, will lop two precious days off summer vacation, June 23 and 24. One more snow day and June 25 will be next.

"We might be in school in July; I don't know," Fairfax schools spokesman Paul Regnier joked.

Among large districts, only Loudoun County, where officials eliminated the suspense yesterday and closed schools for the week, apparently will not have to make up snow days. Loudoun's calendar is five days longer than required, and its school day is 25 minutes longer. Spokesman Wayde B. Byard said Loudoun students could miss as many as 14 school days before losing vacation time.

In such outer districts as Loudoun and Fauquier County, which is taking its 11th snow day today, schools were closed because of miles of unplowed rural roads. In more suburban districts, the problem was impassable parking lots, where plows had pushed snow into huge, space-eating mounds.

Prince William schools Superintendent Edward L. Kelly said the maintenance chief told him schools could open "if we can tell the high school students they have to ride the buses."

In urban districts, the issue was sidewalks. "We have so many walkers," Prince George's schools chief Iris T. Metts said, noting that many of them would have been walking in the road.

Such decisions left parents and children to invent entertainment for a fourth snowy day. After watching three videos and making a fourth with friends (to Pink's "Just Like a Pill"), Mallory Glover, 8, a third-grader at Greenbriar West Elementary in Fairfax, finally changed out of her pajamas yesterday and went sledding.

"It's a rest of my brain," she said. "I don't like that it takes off my summer vacation, but otherwise it's nice."

For her mother, Christine, snow days were a nice diversion compared with what she had been preparing for. "We were getting ready for the terrorist attacks," she said. "Now, though, the kids are starting to get stir-crazy. . . . The novelty of a snow day has quite worn off."

It certainly has worn off for school administrators, most of whom have spent more than the two to five snow days they budgeted. Building snow days into calendars is part experience, part guesswork -- leaving lots of room for luck.

School officials in Prince William calculated that they've had an average of 4.6 snow days a year for the past 11 years, and they had budgeted four snow days this year, according to School Board Chairman Lucy S. Beauchamp (At Large). Today, Prince William is using its seventh, which means students will lose two teacher workdays and the first day of their spring break, April 14.

Kelly said he's had to take part of spring break only once in his 15 years as superintendent. And how did parents take it?

"Not well," he said.

Administrators in Montgomery and Prince George's counties said they plan to apply for a state waiver that would excuse them from making up some of the missed days. Maryland officials said they consider such applications case by case.

Virginia law requires school districts to make up the first five snow days but gives them a pass on the next five. If they miss more than 10 days, makeup days are required again. Only school districts that have missed more than 15 days can apply for waivers, Virginia Department of Education spokesman Charles Pyle said.

Students in Arlington County, which budgeted two snow days and is in its sixth today, will be in school on Memorial Day and for three extra days in June.

D.C. schools, also closed today, are 3 1/2 days over budget, but Superintendent Paul L. Vance said he'll wait to see how many more days must be made up before deciding how to do it.

Fredericksburg schools budgeted five snow days and are using their fourth today. Superintendent Dale Sander said that if he goes over the limit, he prefers to schedule makeup days during the school year rather than at the end, "because it's past testing time, and kids are antsy to leave."

Calvert County officials don't build snow days into their calendar. They designate makeup days, and so far they will need to use five: two days from spring break and three at the end of the year.

The days recouped aren't always equal to the days lost, according to Deputy Superintendent J. Kenneth Horsmon. He is concerned about the Maryland School Assessment, the new state test to be given in grades 3, 5, 8 and 10 during the first week of March.

"We're losing precious, precious instruction time," Horsmon said.

School buses remain snowed under in a bus yard in Gaithersburg, where most main roads had been plowed and many side streets had not.