At age 33, Sheryl Owens said, she is too young to be a strict "old fuddy-duddy" teacher.

But for the past five years, she explained, she "tried to enforce standards, tried to make sure the kids learned something and tried to keep the doors open for them instead of just passing them along."

Some of the students in her English classes at Fairfax County's Mount Vernon High School responded to her demands, she said, but many did not. When she gave low grades, parents as well as students often complained.

Increasingly, she said, school administrators joined in the complaints, accusing her of setting standards too high and applying them inflexably. They would urge her often to "find some way" to raise a student's grade she said.

Owens said she never changed a grade despite considerable pressure.

Last month, she quit, resigning to take a job teaching at Groton, a private boarding school in Massachusetts, whose graduates include Franklin D. Roosevelt.

"Groton's a wonderful school," Owens said.

"But really what I wanted to do was to stay at Mount Vernon. I enloy teaching those kids, the full range of kids - the dum-dums and the bright lazies as well as those who are motivated . . .

"I couldn't stay, though. There was a point beyond which I couldn't let my standards down any longer."

To Fairfax school officials Owen's problems are unusual in a school system widely regarded as one of the best in the country. To Owens and other critics, though, they are symptomatic of the difficulties that even well-regarded schools can have in maintaining high academic standards.

"Nobody is going to be too hard on a teacher for being too easy," Owen said. "If the kids pass, you won't be questioned. If they fail, then you will be. The concern of a lot of people is just to get the kids graduated."

After her first semester at Mount Vernon in 1973, Owens said guidance counselors told her that she couldn't fail students for not doing homework.

"I acquiesced in that," she said, by setting up a system under which students were required to do homework only if they wanted As or Bs. Students could choose to do in-class assignments if they wanted nothing more than a C.

When she failed a star athlete, she said, a counselor asked her to raise the grade so the student could get a sports scholarship to college. She refused.

Later, she said, the principal urged her to accept a paper from a boy who had repeatedly missed deadlines instead of failing him. The boy's mother complained, she said.But the boy himself wrote her a note: "Please excuse anything my mother might say. I know my grade was fair. Owens didn't change it.

In many cases, she said, when students complained that she was too hard, school officials, including guidance counselors "would commiserate with the students and tell them I was unreasonable instead of supporting me and urging them to try harder."

Once, she said, she failed a senior even though his scores on college entrance examinations were exceptionally high. She said the boy missed more than a third of his classes and did little work in the ones he attended, often dozing off in his chair.

A day before graduation, Owens said, the principal asked her to prepare an assignment the boy could do overnight and to let him pass the course if the work he turned in was satisfactory.

Again, Owens said, she refused, and the boy did not get his diploma, although later she gave him a special makeup assignment to complete by mid-July.

"I have to live with my conscience," she explained.

Mount Vernon principal Thomas Hyer said he would not comment on Owen's specific charges, but he said he has never asked a teacher to raise a grade.

"Sometimes I've asked a teacher to consider some other work that a student's done so he wouldn't have to fail," Hyer said, "but I've never told anyone to change a grade."

The principal praised Owens as a "110 percent dedicated teacher."

"She works 30 hours a day," he said, "and when other people don't do that much, she has trouble dealing with it."

Fairfax school superintendent S. John Davis said he had "some concern" about Owen's complaints when she had a conference with him last winter. When he investigated, Davis said, he found "there were some problems on her side too . . . I thoughht the situation should be handled at the local school."

"I believe in raising standards," Davis said, "and we support teachers 100 percent when we feel they are right. But there's got to be a little flexibility . . . There has to be a little humaneness and there wasn't in all these cases."

Owen said Davis suggested that she transfer to one of the county's "more academic" high schools, such as Langley, where achievement test scores have been considerably higher than those at Mount Vernon where scores nonetheless are comfortably above national norms.

Davis said he never called Langley "more academic" than Mount Vernon, but did suggest that Owens might be happier there.

During the summer Owens teaches philosophy to some of Virginia's brightest high school students at the Governor's School for the Gifted at Mary Baldwin College in Staunton. Before she came to Mount Vernon, she taught for five years in private schools. Before that, she received a bachelor's degree at Mount Holyoke College and a master's degree in English at Middlebruy College.

Owens said she went to elementary school and high school in Park River, (N.D.) a small town (population: 1,200), where her father was a Methodist minister.

"I grew up with a bunch of farmer kids," she said, "and in school those kids had to work. I remember one teacher who cared about us all. Boy, did he make us work. We gained a lot of self-respect because of that."

But Mount Vernon High, a school with 2,300 students and 120 faculty members, she said, "the values are so topsy-turey, so sentimental. I had to fight the administration to teach the kids. They think we're being really kind by giving them that diploma even if they haven't done the work. They say we ought to understand because they're poor, because their parents are getting divorced, because they're on drugs, because they're bright but just not working hard . . . I have to live with my conscience. I just can't hand out grades."

She said she thought administrators should give strong support to teachers when students and parents complain about grades.

Hyer said that as principal he has "to look at the whole situation affecting a student, not just the work in a particular course.

"The thing that some teachers don't realize," he said, "is that we're in a different era now. There's a code of student rights and responsibilities. They have the right to complain (about a teacher), they have the right to appeal . . . That's life. I can't give a teacher immunity. I don't have it myself."

Bryan Avery, president of the year's senior class at Mount Vernon, said he received a C from Owens while his other grades were As and Bs. Before he was assigned to her class, Avery said he had heard about "the infamous Miss Owens and I was scared to death." For the first marking period she gave him a D.

"I really hated her. It was really rought," Avery said. "We never had such a work load and it hit me hard. I tried to get out of her class, but my parents made me stick to it. I'm glad I did."

Avery said Owens had more rules than any teachers he had ever encountered. "But they were fair," he said, "and she stuck to them. A lot of other teachers might add a point if you were close (to passing) but Miss Owens won't give people that one point if they don't deserve it.

"A great many things Miss Owens did were completely strange to the students at Mount Vernon," Avery said. "She definitely goes to her standards all the time, and to change them or bend them would just tear her up."