At Rippon Middle School in Woodbridge yesterday, hundreds of students lined up in the cafeteria to sign a letter to Concord (N.H.) High School that read simply: "We share in your grief."

Fourth graders in Takoma Park debated the safety of space travel, and most agreed that progress carries risk.

In Joan Lawson's ninth grade English class in Fairfax County, students discussed a passage in a novel that talks of the need to feel sadness -- but not despair -- for the world's troubles.

The day after the space shuttle Challenger exploded in flames 10 miles above the Atlantic Ocean, Washington area schools struggled to help students accept and learn from the tragedy that killed six astronauts and New Hampshire teacher Christa McAuliffe.

Many schools lowered their flags to half-staff in respect for the dead. Some observed a moment of silence.

And in classroom after classroom, teachers wrestling with their own feelings of loss talked about the fatal flight in a hundred different ways: As a metaphor for the fragility of technology, as a lesson in courage, as a marker that will fix that day forever in their students' lives.

Teachers said many students were upset by the shuttle disaster, although not to the point of hysteria that can cause schools to bring in extra counselors. Some school officials reported all was calm.

"It seems business as usual here," said Gary Miller, principal of Frost Intermediate School in Fairfax County. "It's not that they're callous. But intermediate kids -- 12-year-olds -- [believe] you're not going to die."

At Piney Branch Elementary School in Takoma Park, science teacher Bonnie Johnson told her fourth grade pupils she felt some "selfish thoughts" when she watched the launch because she had applied for the seat McAuliffe won. But shock quickly followed, she told them, and "now I feel extreme relief that I was not a part of this."

She encouraged her pupils to talk. One expressed anger at NASA for letting the launch go forward despite the delays that had plagued the mission. "Why did they continue to push?" demanded another.

The perils of space travel were very much on the minds of her pupils, some of whom want to be astronauts. "I would never do it. It's too dangerous," said one.

But most nodded in agreement with 9-year-old Eric Chang, who said: "When you are learning to walk, you fall down, but you don't stop trying." Said another: "To do anything important takes a certain amount of risk."

A school assembly was held at the Thomas Jefferson High School for Science and Technology in Fairfax, where many of the 400 students plan careers in space-related fields and where language teacher Judith M. Garcia was a finalist for the berth on the shuttle that McAuliffe won.

"We talked about the sorrow, the hurt and the pain, but that reality is that you have to go on," Principal Ray Volrath said. Volrath also told the students that their teachers may be fighting sorrow, too.

Several students approached Thomas Jefferson teacher Lawson later in the day to ask how she felt. Most told her they were saddened and upset by Tuesday's unexplained explosion. But a few, she said, made remarks "not in good taste."

So Lawson pulled out William Saroyan's "The Human Comedy," which her students have been reading this month. In it, a 14-year-old telegraph messenger -- who is just a year older than many of her ninth graders -- cries over the messages of death he must deliver in 1942, during World War II. He seeks comfort from his mother.

Lawson reread that passage with her students: "She says a good man cries for the pain of the world, but he does not despair for it." Afterward, she said, the joking students were subdued -- by the novel and by their classmates' criticism.

Others students received solace from writing letters of condolence. The National Junior Honor Society at Rippon tacked up an 8-foot-long sheet of butcher paper on the cafeteria wall for its one-sentence letter of condolence to Concord High School. By midday, it was crammed with signatures, and a 6-foot-long second page was half full.

"We're hoping that can lift their spirits," said Scott Tyo, 13, the society president. Social studies teacher Patricia Dunlap, who cosponsors the honor society, said, "It's something they're accomplishing. It's helping them to sign it."

Anna Cagle, too, believes that "one way to help children deal with death is to have them do something constructive." So her fifth grade class of 28 pupils at Camelot Elementary School in Annandale wrote letters of condolence to the families of those killed, most of them to the McAuliffe family.

"I am proud of her for having the courage to go to space, and I am sure you are proud of her, too," wrote one pupil. Another child wrote: "I hope this never happens again and I am really sorry she's dead."

Pupils at Patterson Elementary School in Southeast Washington, who had met astronaut Dianne Prinz the morning of the crash, had a minute of silent meditation yesterday. A dozen third graders read a poem, "Living is Giving," over the school loudspeaker, and one explained that it was all right to feel sad.

"The building was extremely quiet today," Principal Jessie Douglas said. "It was like the building was empty."

In Alexandria, where every pupil in the public elementary schools had watched the shuttle mission take off and disintegrate, many principals read a letter over their public address systems.

Written by Shirley Urquia, director of the city's elementary education program, it said in part: "The quality of our lives today is largely determined by the countless past explorers who forged ahead into the unknown."

"The whole idea of the letter," said Urquia, "is to help children put into perspective the fact that we have always taken risks -- and that achievement demands that we continue."