Watching Sara Jane Knight teach American history, you get the impression that she not only knows her subject inside and out and loves to share her knowledge, but that she enjoys her students as well -- cares about each one. A gift for rapport; a talent for zeroing-in. A special knack for down-to-earth, give-and-take discussion. About history, philosophy, current events, thoughts and ideas.

On a recent Friday, she stood before a class of about twenty-five 16-year-olds discussing what Plato's "Allegory of the Cave" can say about man's perception of the world around him.

"Why is it so painful to see the real world?" she asks her students, referring to Plato's character who escapes the confines of the cave.

"He was so long in the shadows," a student volunteers.

"What does light symbolize throughout history," Knight throws back.

"Knowledge," a student answers.

"Truth," says another.

The classroom door opens and a boy walks in a few minutes late.

"Hi, Eddie. Everybody has been waiting for you to appear," she says, smiling. "Thank goodness you've arrived."

Her manner is easy, low-key, good-humored.

"Everybody on track here?" she asks, scanning the class. "We're dealing with Plato here, guys. Pretty deep thought."

"Is there out there somewhere the big T? The ultimate truth and reality?" Knight asks again.

The question sparks more discussion. On knowledge, perception, religion, Thoreau, Martin Luther King and, finally, the American Constitution.

Knight's students at Arlington's Yorktown High School say they are not surprised that their history teacher has been chosen as Arlington's teacher of the year and recipient of The Washington Post's Agnes Meyer Outstanding Teacher Award.

But clearly they are thrilled.

"She deserved it," said Kelley Robinson, a 16-year-old junior. "She's hard but she explains everything. She has a positive attitude toward every student."

"The way she teaches, you don't really get bored," said Mike Barton, another 16-year-old junior. "She likes you to be happy in your class."

"She has a very good understanding of people," said Sara Hansen, 17, who is taking American history this year as a senior. "She talks to you not like you're a student -- not like you're a teen-ager. It's a bit rare."

Steve Kurcis, Yorktown's principal, praised Knight.

"In public education you need teachers who can not only deal with kids who are self-motivated but also with students who are hard to teach," he said. "Mrs. Knight has that ability."

Knight, 52, is beginning her 30th fall as a teacher in the Arlington public school system. She began teaching at Williamsburg Intermediate School, formerly known as Williamsburg Junior High School, in 1955, after graduating from the College of William and Mary.

She taught American history, English and social studies to eighth graders for six years and came to Yorktown in 1961, where she has spent most of her time teaching American history to juniors. Currently, she is chairman of the school's social studies department.

Knight said she feels flattered to have been chosen for the award.

"There are many, many outstanding teachers," she said, referring to Arlington's nearly 1,000 public school teachers. "You know you're representing a lot of good people."

Knight said she is often asked what makes her want to return every autumn, again and again to history, to students and to Yorktown.

"I think being with young people keeps you young," she said. "I just love teaching history and I love seeing kids learn that they can like it.

"If you find out one of their interests and spark that, they will carry that over into other things."

In 1965, Knight helped design a course called American Civilization, in which American history, literature and culture were taught all at once during a double period. Knight team-taught the course for 16 years until a sharp decline in enrollment forced it to an end.

"It was very exciting," she said. "Students still ask about it."

Knight said she can't remember a time when she did not want to be a teacher.

"I always knew I wanted to teach and I loved history," she said. "I think you get such an understanding of people and their times."

One of the most important lessons a student of history can learn, Knight believes, is "how an individual can make a difference in society."

"That's so important," she added.

Knight said she believes learning is most effective when it's fun.

"Students learn best in an atmosphere of open inquiry," she said. "If you reduce teaching to a bland summary of facts, you are doing them a disservice."