If there is one thing Katie Boltz has mastered in high school, it is how to use every minute of her day efficiently. With five Advanced Placement classes, the Dulaney High School senior doesn't text her friends or watch TV so she can focus on homework — but still only manages three or four hours of sleep some nights.

"Originally, I thought I would really like all of these classes," the 17-year-old said, adding that when she is overwhelmed, she questions the decision to take so many demanding classes at one time. "It is definitely a lot."

Boltz is one of a growing number of students in Maryland and throughout the nation juggling a full plate of college-level classes in high school. In the past decade, the number of students nationwide who take more than three AP exams a year has doubled, to about 175,000.

Designed a half-century ago to give a few thousand elite students a chance to skip introductory college classes, Advanced Placement is now the required portal to college for any ambitious teen.

But its widespread acceptance as a national gold standard has altered the nature of high school for students like Boltz, some critics say. They see an education system that rewards top students who take 10 to 12 AP classes during their high school careers — the equivalent of more than a year of college — but narrows the choice of classes they can take and creates undue stress.

The system is driven partly, they say, by colleges that use Advanced Placement — the number of classes taken and exam scores earned — to rank applicants, and by savvy local school administrators who want to boost a school's national rankings. School districts routinely point to those rankings, giving principals an incentive to get more students to take the classes.

Now some parents, educators and even university admissions officers are rethinking the role of AP classes. A Baltimore County parents group wants teachers and administrators to be more upfront about the demands of the classes.

The admissions office for the University of North Carolina at Chapel Hill is advising applicants that there is no benefit from taking more than five AP classes in high school. And a New York public high school has dumped the program in favor of what it sees as a better college preparatory curriculum.

"The relentless marketing effort by many principals to place a greater number of kids into a greater number of AP classes — all in a single semester, as early in a student's career as possible — is backfiring," said Mary Ellen Pease, a co-founder of Advocates for Better Course Choices in Baltimore County Public Schools and the parent of two recent county graduates.

Such protests represent a minority voice, and educators and parents say they have little influence over such a national juggernaut. Most education leaders across the nation have embraced the expansion of AP, seeing it as a way to raise achievement and provide educational equity to students in poorly performing schools.

But its ever-expanding use has meant that high-achieving students are loaded with the courses while some unprepared students at low-performing schools flounder and fail. A Baltimore Sun investigation last year showed that many students are given high grades in the AP classes but then fail the exams.

But AP teachers say having a tough national exam that only 60 percent of test takers pass has pushed students and schools to a higher level of achievement. And Boltz and her fellow students say they are glad to have taken challenging classes that prepare them for AP exams.

Trevor Packer, who leads the AP program for the nonprofit College Board — with members that include more than 6,000 colleges, universities, school districts and education organizations — has concerns about students who take too many AP classes but doesn't think it's a widespread problem.

"I don't love the idea of students taking AP just so they can stand out in college admissions," he said. "I want students to take AP because they want to learn at a higher level and they are passionate about that subject. There is some harm happening there that we all want to acknowledge. ... I just don't think the data support that as a national concern right now."

However, Packer's organization encourages students to take the classes, handing out awards to graduates who have taken a high number of the exams and earned top scores.

Entrenched program

Maryland is considered by education experts to be a bellwether state for AP. It led the nation in expanding the program by prodding schools to offer more of the classes. Top-performing high schools such as Dulaney in Baltimore County offer as many as 25 AP classes, from art to calculus to history. And about 30 percent of the state's graduating seniors have taken and passed an AP exam — a higher percentage than any other state.

Few in Maryland or across the nation question the value of encouraging well-prepared students to try AP classes. The vast majority of students — about 80 percent nationwide who take an AP course and the corresponding exam — take just one to three classes a year.

"When taught properly, the richness of Advanced Placement courses allows students to experience content at a depth normally unavailable to them in other high school courses," said Martin Stranathan, Boltz's AP biology teacher at Dulaney.

Baltimore County schools Superintendent Dallas Dance said it is important to offer AP classes to students as a way of preparing them for college. "When you talk to most universities, they want to see AP on the transcript," he said, adding that he would like each county high school to offer at least 10 AP classes.

Students at Dulaney said taking 10 or 12 AP classes during high school is considered routine among those at the top of their class. They thrive on the community of high achievers who enjoy working hard to get good grades and high scores on the AP exams.

But they also say that maintaining a balanced life with classes, activities and athletics is difficult.

Joe Pezzulla, 17, who takes five AP classes, said he and many students have "that feeling that you need to overload your plate and push yourself on things you don't care about. … There have only been a couple times when I have been in a class that I have been extremely passionate about."

Students say they would have opted for challenging high school-level classes — one notch down from college level — but most of those are no longer offered at Dulaney. The honors classes that are still taught, they say, often are too easy and are taken by students who are struggling to pass.

"If there were more honors classes that were offered that were more challenging, I would have taken them," Boltz said.