Christa McAuliffe -- who is about to have the extraordinary experience of being the first schoolteacher in space -- believes that history unfolds in the lives of ordinary people. That is why, when she became pregnant in 1976 with her first child, she began to keep a journal.

The entries -- what she did, how she felt -- were not for her but for posterity: "I felt that when the children are old," she said, "and they're starting to think about their own careers and marriages, I'll be able to hand them part of my life.

"I would have loved it if my mother had said, 'Here: This is what my life was like."

McAuliffe, who was chosen from among 10 finalists for a space-shuttle flight in late January, is about to see her life change dramatically as she takes a sabbatical from Concord High School and immerses herself in a training program with the National Aeronautics and Space Administration.

Characteristically, she intends to keep a journal -- testimony to her conviction that daily life is as crucial to history as chronicles of wars and politics. "Is that an unusual role for women -- to donate things?" she asked students in her women's history class one day last spring.

Concord's Main Street, the scene today of an outdoor festival, erupted in cheers when news of McAuliffe's selection was announced over the radio.

"I started crying when I heard," said Mary Ann Lakevicius, owner of Diversi's Market on Main. "I'm so happy for her. It's just something to be the first teacher to go into space, and to think she came from Concord, New Hampshire."

McAuliffe's husband, Steve, a Concord lawyer and her high school sweetheart in Framingham, Mass., said he "found out on the radio, like everyone else. I'm spellbound, dumbfounded and thrilled. Everybody who knows her thought she was a perfect choice for the job."

When McAuliffe called him at his office after the official announcement, she was put on hold because he was in a meeting -- with a reporter. When her call was put through, he said, "You haven't made plans for tomorrow, I hope, because I have." She is to be the impromptu star on Saturday of the town's long-scheduled Lions Club parade.

"I just let out a yell as soon as I heard" the news, said Ron Brown, a colleague of McAuliffe's at Concord High. ". . . She's such a dedicated teacher, . . . and she's a very attractive person -- visually, vocally. She brings those characteristics to class, her enthusiasm and her excitement. I'm sure she'll bring those characteristics to the space program."

McAuliffe is remembered as "a great teacher" by John Hagan, former vice principal of Thomas Johnson Junior High in Prince George's County, where she taught English and social studies in the mid-1970s. "She really and truly loved the kids," said Hagan, now principal of Bowie High School.

She taught at Benjamin Foulois Junior High School in Prince George's from 1971 to 1973 and at Johnson for the next five years. Her husband was a law clerk for Rep. Steny H. Hoyer (D-Md.), who was then an attorney in private practice and serving in the state legislature.

"I think it's super," Hoyer said today of McAuliffe's selection. "She's a good lady. They chose well." He said McAuliffe used to bring her students to his Annapolis office during General Assembly sessions. She and her husband moved to Concord in 1978 when Steve McAuliffe was appointed an assistant New Hampshire attorney general.

Anne Gfroerer, 17, graduated from Concord High last spring after taking McAuliffe's classes -- American foreign policy, American culture, women's history and law -- for three years. In one, Gfroerer said, McAuliffe divided the class into groups and assigned each group a decade to describe to the class.

Some students came dressed in period clothes, others performed dances of the era, some acted out monologues. "It was a lot more interesting that having someone up front giving us notes," she said.

"She can relate to every student in her class," Gfroerer said. "She's got this outlook that says, 'What the heck, you've got to live life.' When she was applying for this, she said, 'I don't know if I'll make it or not, but I'll try it. It'll be fun.' That's the attitude that she goes into everything with."

McAuliffe, 36, has said she has the soul of an adventurer: In another time, she said, she would have shipped over on the Mayflower or gone West with the pioneers. The shuttle mission was a natural goal -- one for which six-year-old Caroline McAuliffe has not always shared her enthusiasm.

Earlier this month, when her mother and the other finalists were undergoing tests at Johnson Space Center in Houston for more than two weeks, Caroline complained about the long absence. "Look, Caroline," said 8-year-old Scott McAuliffe, setting her straight, "this is a once-in-a-lifetime chance."

It was one of many separations that the McAuliffes will face -- and their durability at long distances was one of the criteria that influenced the selection. McAuliffe will have to undergo 114 hours of training before the flight and commit a year to NASA afterwards.

McAuliffe remembers the United States' first space shot over the Atlantic Ocean in 1961, with another New Hampshire astronaut, Alan B. Shepherd Jr., aboard Freedom 7 -- and President John F. Kennedy's promise that the United States would put a man on the moon. She also recalls Neil A. Armstrong's moonwalk in 1969: She and her husband, driving their Volkswagen through Pennsylvania in a rainstorm, cheered.