"Drop your jaw, Nick!" Ms. Boley is saying, standing indomitable at the front of the chorus classroom. "Nick, drop your jaw!"

But Nick, a fresh-faced underclassman wearing jeans and a long gray polo shirt, isn't dropping his jaw. At least, he isn't dropping his jaw enough to suit Ms. Boley.

"If muuuusiiic be the food of loooove, sing on, sing on!" he sings, working his way through a complex vocal arrangement that students in Ms. Boley's upper-level concert choir class are expected to master. Even as Nick sings, his jaw remains clenched, so Ms. Boley takes hold of it, grasping his jaw and tugging it downward while Nick, gamely, keeps singing.

Before long, Ms. Boley is scanning the room for someone else to call on. And the person she spots is: Katy Haddow.

Katy has been dreading this possibility since she got to school this morning. A blond, sweet-faced junior, Katy very much likes concert choir, an advanced choral music class at Stonewall Jackson High School in Manassas. But she hates having to sing by herself in front of some 75 classmates, many of them strangers. It makes her so nervous, standing there singing while Ms. Boley assesses her diction, her breathing, her pitch and, often, her ability to sight-sing an unfamiliar song, cold, from looking at the score. So nervous does it make her that she's adopted a strategy to reduce the likelihood of this happening. Nestled halfway up the risers among the second sopranos, Katy has been sitting with her hands demurely in her lap, her eyes carefully directed floorward so as to avoid making eye contact whenever Ms. Boley sweeps the room with her gaze.

That strategy having failed, Katy obediently makes her way down the riser steps, along with several others similarly summoned. "If music be the food of love, sing on!" they sing, and while they are singing Ms. Boley goes up to one girl and pokes her abdomen so that the girl stands up straight and sings louder. And then Ms. Boley pokes another girl's abdomen, and this goes on until, mercifully, the song ends before Ms. Boley gets to Katy. Even so, the whole experience raises anew, in Katy's mind, the question of whether she should drop concert choir, which, just weeks into her junior year, is turning out to be her most anxiety-producing class. Even IB history, Katy is starting to think, might be less stressful. IB history! Less stressful!

Which is saying a lot. IB history, if Katy decides to switch, is going to have two hours of homework a night, plus a major exam at the end of the year. That final exam will, of course, be in addition to the other tests Katy will take this year -- the SOLs and the SATs -- and in addition to the considerable workload of her other classes, English, Spanish, algebra II and chemistry. Plus, Katy is

already signed up for IB anthropology, which has an even heavier workload and its own end-of-year exam. At Stonewall Jackson, a large, high-performing public high school, the IB, or International

Baccalaureate, classes are similar to AP, or Advanced Placement, courses. They are the most advanced, most competitive classes, the classes that may seem to separate the students who are college-bound from the students who are not. One of the many things worrying Katy is which category she will fall into. The college-bound? Or the not?

"I feel like if I don't take IB classes, I'll never be anything in life," Katy says. "That's what our teachers are telling us. Our IB coordinator, she will come into our class and tell you to sign up for all the IB classes that you can, girls, or you're not going to make it in college or be anything."

In her free-floating anxiety, her belief that every single course decision is going to have a crucial and permanent impact on her future, Katy Haddow is, it turns out, a typical 16-year-old girl. This summer, Katy took part in the Post-Kaiser-Harvard poll of area high school students and their worldview. She is representative of one of the poll's more striking findings, which is that in the final two years of high school, D.C. area girls report far higher levels of stress than boys do. When asked how often they experienced stress in their lives, roughly one-third of ninth- and 10th-grade boys and girls answered that they felt stress "frequently." When they moved into 11th and 12th grades, however, the percentage of boys who felt stress "frequently" remained stable, while the number of stressed-out girls shot up to 56 percent, with the overwhelming majority of these citing school as the main source of stress. Overall, D.C. area teenage girls reported higher levels of stress than teenage girls did nationally, which probably has to do with the fact that this is an urban area with so many high-achieving families -- whose expectations, it would seem, affect girls even more powerfully than boys.

"A lot of things are hitting home now; we're in the homestretch of high school," Katy reflects. At the year's outset, she has already changed her schedule twice, dropping IB English in favor of regular English because, although she spent the past two years taking pre-IB English, something in her just snapped when, at the beginning of the summer, she confronted the prospect of reading four heavyweight novels and writing papers on them during the meager 10-week vacation. She also decided to switch from oceanography to chemistry because oceanography looked like a lot of group projects, and she was afraid that the other kids would leave the projects to her. Now she is pondering the crucial question of regular history versus IB history. Her aim is to strike a balance in which she takes enough IB courses to get into a good college, but not so many that she spontaneously combusts.

"My problem right now is that I'm feeling like I'm not going to be able to get into a good school; I'm going to end up working at McDonald's," worries Katy. "I break down every day. It's horrible, all of this pressure from school. I always feel stupid all the time, because of these IB classes: I'm not taking enough, or I'm not doing well enough."

On the face of it, this off-the-charts stress may seem surprising. More than a decade ago, several studies, including the American Association of University Women's landmark "How Schools Shortchange Girls," found that girls were disadvantaged in school compared with their male counterparts. Since then, however, girls have made so many advances that the positions have entirely shifted. In our poll, for example, 44 percent of girls reported making mostly A's, compared with just 26 percent of boys, a finding that is amplified in national statistics. According to a 2004 report issued by the Department of Education's National Center for Education Statistics, high school girls now display higher educational aspirations than their male peers, and are more likely than boys to enroll in college immediately after high school. More girls than boys are valedictorians; more girls than boys participate in extracurriculars (except for athletics); far fewer girls than boys drop out of high school. In the past 20 years, girls have become much more likely than they once were to take advanced math and science courses, and to push themselves overall. In 2002, the majority of AP examination takers -- 56 percent -- were, like Katy, female.

In short, the strides for girls have been tremendous, and in this, too, Katy is representative. Last year she made A's in all of her classes, including biology, "where I got, like, 103." Her GPA is 3.94, and she ranks 23rd in her class of 450 students. All of which suggests that stress and achievement are related: Up to a point, it is the anxiety that girls like Katy are feeling that compels them to push themselves so hard and, as a result, do so well.

But there is anxiety, and there is anxiety. Notably, the 2004 federal report also found that even as girls are performing better and better, their enjoyment of high school is plummeting. In what may be the dreariest evidence of gender parity, federal statistics show that girls, who back when they were being shortchanged liked high school more than boys did, now dislike it at least as much as boys do. "The percentages of both male and female seniors reporting positive feelings toward school sharply declined from 1980 to 2001, with female students' positive feelings toward school declining at a faster rate," the report notes. This finding is deeply felt by Katy, who despite how well she is doing, despite how great her school is, how diverse, how high-quality, says with conviction that "the sooner I can get out of high school, the happier I'll be."

In a way, Katy's comment strikes, for a girl, a rare note of optimism, a passing hope that somewhere after high school life might be easier. This is unusual: Our poll also found that girls, by and large, expect that life is going to get worse, not better. Across a broad range of measures, girls' views of the future tend to be more negative than boys'. Just 51 percent think the best years of the country are ahead of us, compared with 65 percent of boys. Only 36 percent of girls think that when they are adults, Americans will be more moral than they are now, compared with 47 percent of boys. And 62 percent of girls think there will be another major terrorist attack in their lifetime, compared with 53 percent of boys. Boys are split over whether children today have a harder time growing up than their parents did, while 60 percent of girls feel that growing up is harder today than it used to be.

In general, girls just seem to worry more than boys do, with Katy an ideal example. "I shouldn't, but I worry about a lot of things," she said just before school started. She was sitting in the living room of the large and comfortable Gainesville house that she shares with her father, a lobbyist, and her mother, an editor who works a part-time schedule organized around the needs of the household. Superficially, Katy's concerns seem excessive, to say the least: a loved and lovely girl with an excellent mind and exceedingly conscientious work habits and a two-parent family and five older siblings -- three of them girls -- whom she values and admires. But family brings pressures of its own. Katy looks up to her siblings and worries that she will not do as well as, for example, her sister Jami, who took tons of IB classes and drove herself crazy but got into the University of Virginia and now, at 27, has a baby and a great job in public relations consulting.

"My sister is a genius," says Katy. "I have all these awesome brothers and sisters. I have so much pressure to live up to what they've done."

"Jami thinks now that high school stunted her growth," Katy's mom, Alice, reminds her youngest. "She told me last night that if she were to choose the most useful class she took in high school, it would be driver's ed. She said, 'It taught me a skill.' Everything else was just extremely stressful. She had to live on so little sleep. She was led to believe, by people she trusted, that if she did not excel in high school she could not possibly succeed in life."

"I think it's true," Katy reflects, "what Jami said about it stunting her growth."

In fact, because of Alice Haddow's experience with her older girls, she has adopted a different strategy with Katy. "I'm sure that if she was one of my older children, I would be pushing her as hard as she wants to push herself," says Alice. Having seen what they went through, however, she now sees it as her role to prevent Katy from pushing herself too hard. She and Katy's father, Mac, have told Katy that she can take only one IB class. If she does switch into IB history, she will have to drop IB anthropology. This dynamic -- Katy wanting to do more, her mom wanting her to do less -- is, Alice Haddow says, their "only source of friction."

"I tell Katy every day there are people who -- Albert Einstein was a high school dropout. Peter Jennings was a high school dropout," Haddow says. "We're just mired in a system that takes this position that huge amounts of stress are somehow beneficial." At the same time, she acknowledges that she has to work at not sending mixed messages. She used to e-mail Katy's teachers to check her grades. "I had to stop doing that," she says. It's a hard balance, too, for parents: You want your daughter to do well, but you also want her, emotionally, to survive. "Girls," notes Haddow, "panic if they're not approved of."

Whereas her sons -- well, that was a different kind of conflict. "You couldn't make the boys care about high school," she says. "They had no concerns whatsoever. Cajoling, yelling, any part of the spectrum in between -- they did not care."

Despite being in the top 5 percent of her class, Katy fears that she won't get into her colleges of choice, Brigham Young University and U-Va. Her family is Mormon. Both her parents went to BYU, and you'd think that would give her some advantage, except that the ranks of Mormons have steadily grown in the United States, and BYU hasn't, or not as much. "When I went there, if you were tall enough to push your money over the counter you could get in," says her father. "Now it's so doggone competitive, you've got to be a high-performing student with not only grades but fairly robust extracurricular activities to get in." In fact, it's really not so grim: According to statistics, BYU admits 80 percent of its applicants, and U-Va. admits about 40 percent. Most of these were in the top 10 percent of their high school class, a criterion that Katy easily meets, and then some. Still, to Katy, failure seems an entirely plausible outcome.

A full day with Katy feels like spending the day on a particularly hilly leg of the Tour de France. Most days, she gets up at 4 a.m. to have time to take a shower and straighten her hair afterward, a 40-minute process that involves a lot of blow-drying and, at the end, curling the very tips. She is not doing this for the benefit of any boy, because she doesn't have a boyfriend and doesn't plan to. "Last night I was with my girlfriend just talking about boys and how horrible they have become," she says, meaning that increasingly, the boys she knows are chiefly interested in one thing. "At the end of the year, last year, the senior guys all started to be very raunchy, talking about how college was going to be just sex with girls. And now I see guys my age, a lot of guys I'm friends with -- like, I was talking to one friend and said: 'Why don't you go out with this girl? She really likes you,' and he said, 'Yeah, she's really cool, but she's not going to put out.' "

Although Katy dated some last year, in technical violation of a household rule against 10th-grade dating, she has decided not to date at all this year, even though she is officially now allowed to. Sooner or later, she suspects, any relationship is going to reach that bottom-line conflict, and she doesn't need the pressure associated with always having to say no. What makes her resolve easier is that her father wants her to date only Mormon boys, and Mormon boys, she says, "are kind of nerdy."

Given this resolve, when Katy gets dressed in the morning, the people she is really dressing for are her female friends, which is a demanding thing in and of itself. With all the blow-drying and tip-curling, she doesn't have time for breakfast before her ride, a senior named Scott Jackson, arrives at 5:30 to take her to church class and then to school. Katy is taking seven classes in all. She has English every day; the other six classes take place on alternate days. Each class is 90 minutes long. If you miss one day, you miss a lot, particularly in the IB classes. This is why IB kids come to school even when they are sick. "If you take a day off, you're going to miss all this work; you have tons of work to catch up. We all get sick in the wintertime, but all of us are still going to school, puking everywhere," says Katy offhandedly.

So packed is the schedule -- and so large is the school, physically -- that during her school day Katy never stops for a drink from the water fountain; never goes to the bathroom; never visits her locker, because it's too far away to get to and still be in class on time. She barely has time to speak to friends, save for an occasional hug with somebody in the hall and, today, a half-hour lunch break. In line for a taco salad, she greets a group of non-IB-type friends, all boys, who are standing in a clump. "They say they're going to, like, drop out of school and go work in California," Katy says, taking her tray and getting a place at the lunch table with her friend Kiersten Hammond, an IB-type girl, and some other IB-type boys. It's 10 a.m., and Katy has been up for six hours.

Throughout her school day, she is constantly reminded that there are people who go on to college and people who do not. In algebra II, her soft-spoken and kindly teacher, Mr. Inyang, tries to convince them that regression analysis really is something they will use in life. "It doesn't matter what you are going to do -- work at McDonald's, go to college -- you will use it," he tells them. There they are, her two life choices: college or McDonald's.

Of course, to get into college you need to have something besides academics, and that is part of the reason why Katy runs cross-country, a grueling sport that involves a five-mile run -- at least -- every weekday afternoon. Today she has a meet, which means that when classes end at 1:50 p.m., she has 10 minutes to find her way to the locker room, change and get on a bus to Culpeper High School, where she waits until her own race at 5:30, which goes extremely well: She places fifth among the girls. Then it's the bus back to Manassas, which means she doesn't get home until 8:30, doesn't eat dinner until 9:30, and then works on her homework until well past 11, meaning five hours of sleep before she gets up and does it again.

And -- pleasure? Well, Katy likes cross-country. She likes IB anthropology, where her first week she was assigned to prepare a presentation on the four schools of anthropological thought about culture. All of the students had to make presentations, and all of them were assigned partners, but Katy's partner told her he was probably going to drop the class. Assuming she would make the presentation alone, she read the chapter and drew up a careful one-page handout on which she wrote a cogent description of each school of thought, underlining key terms and spelling out the differences for the benefit of her classmates. Then she heard from her partner, who said that he was not dropping the class after all. So she e-mailed him her outline. He cut it in half and sent it back. "He's smart like that," says Katy, sincerely.

She hands in the report, which is choppier than the one she wrote, and takes her seat to listen intently as their lively and erudite teacher, Ms. Ellis, introduces them to the pleasures of anthropological study. This particular IB class seems to have an equal complement of boys and girls, suggesting that boys, too, feel motivated and ambitious, maybe even . . . stressed.

Earlier today, however, Katy's friend Scott Jackson disagreed. "Boys don't care," he said, emphatically; boys don't feel stressed because boys know that everything will turn out okay. Hearing this surprised Katy, who thinks of Scott as one of the few boys she knows who feel as much stress as she does. "He gets stressed sometimes to the point where he can't even talk," says Katy, raising the question of whether girls are in fact more stressed, or simply more willing to admit it. In this case, the evidence would suggest both.

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Q: In general, how often do you experience stress in your daily life -- never, rarely, sometimes or frequently?

Percentage of local teens saying frequently

Local girls ... 42%

Local boys ... 28%

Q: What is the biggest source of stress in your life?

Based on local teens who experience stress

School ... 60%

Family issues ... 12%

Friends or people you are dating ... 7 %

Concerns about the future ... 6%

Work ... 3%

All others combined ... 12%

Liza Mundy is a Post staff writer on leave.