CLAIRE HUANG, a 17-year-old at Lexington High School, has crafted the kind of academic schedule that would put most college freshmen to shame. This year, the senior has almost entirely filled her day with five yearlong Advanced Placement classes —physics, calculus, statistics, French, and economics —as well as two semester-long English electives. Just about the only signs that she’s still in high school are band and gym.

This year represents Huang’s toughest AP lineup yet, but she’s been building toward it for years. As a sophomore, she took AP biology and scored a 5 — the highest grade possible — on the standardized exam at the end of the year. As a junior, she took AP courses in chemistry and US history, then studied the AP Chinese and psychology curriculums on her own. She took exams for all four of them that spring and scored 5s across the board. (For the record, she also recently earned a perfect 800 on a math SAT subject test, an exam she took on top of the traditional SAT.)

So if all goes according to plan, Huang will graduate in June with perfect scores on 10 AP exams. And with a little extra luck, that record will let her skip a semester or two of introductory classes in college, giving her the chance to take more in-depth classes sooner. But Huang is focused on more immediate goals. She wanted to challenge herself with the toughest high school classes available, she says, but she also hoped to find a way to stand out among her peers on her college applications. She has her sights set on a handful of elite private colleges and universities. 

It’s no secret that going to a top-ranked high school like Lexington can give students a head start in the race to a top college, but the odds of winning are slimmer than ever. For one, admission rates to the country’s premier liberal arts colleges have never been lower. In 2002, the Ivies accepted between 10 and 28 percent of applicants; by 2010, some of the schools’ acceptance rates had dipped to as low as 7.2 percent. Meanwhile, at least 10 percent of Lexington’s 500 graduating seniors easily have what it takes to succeed in the Ivy League, says Gary Simon, the high school’s recently retired math department head.

Huang knows all of this, which is why she hopes her AP classes will give her an edge. “Since there are so many students and no class ranking [in the school], there has to be a way that students can kind of show themselves off,” she says during an interview at Lexington’s Russian School of Mathematics, a private tutoring operation where she has taken extra classes. (When calculating GPA, some schools give slightly higher weight to AP and honors classes, but Lexington does not.)

Not that long ago, Huang’s academic accomplishment would have been a surefire way to show off to colleges. But in today’s most competitive public and private high schools, schedules like hers are looking more and more common. State data show that at public schools like Newton North, Newton South, and Wellesley, about half of the juniors and seniors take at least one AP class. About 60 percent of Lexington High upperclassmen take at least one AP course. At Boston Latin School, 93 percent do.

With more students overall in AP classes, applicants struggle to stand out. Making the competition even stiffer, the most driven students, the ones like Claire Huang, are taking eight or more of them. And the more students who take eight classes, the less impressive eight classes begins to seem.

“The numbers are rising, but at some point, there’s got to be an upper limit,” says Brad MacGowan, a college counselor at Newton North. “If it’s college-level work, how can we expect all high school students to do it? If all of a sudden all high school students can do it, then it’s not really college-level work.”

And yet as the AP frenzy increases, few students are willing to become the first to cool it. So the enrollment numbers and full course loads just keep growing. “It’s a runaway train,” says Simon. But since the application process is so intense, says Huang’s mother, Charlene Sui, with a hint of resignation, “there’s no way to stop it.”

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