One of the strongest arguments for taking the classes, proponents of AP say, is that they can save students thousands of dollars in college tuition. But the No. 1 reason that U.S. students cite for taking the classes is the lift AP can give their college applications, a College Board survey showed.

"I don't think getting the credit is a huge incentive for the students who are looking at competitive schools," said Dulaney senior Amica Phillips.

Some colleges are raising the exam score that students must earn to get credit. A passing score is considered a 3, on a scale of 1 to 5, but more colleges are requiring that a student obtain a 4 or 5 to receive credit.

University of Maryland, College Park and the Community College of Baltimore County both require students who have scored a 3 on the biology exam to take the introductory class.

A handful of the most selective colleges, including Amherst College and Massachusetts Institute of Technology, do not give credits for AP, though some departments will let students skip introductory classes.

Dartmouth's faculty voted last year to do the same. Hakan Tell, a classics professor who heads Dartmouth's Committee on Instruction, said the faculty was concerned that students had gaps in their knowledge when they didn't take the college's introductory courses.

"There is a qualitative difference in work done in high school and work done at Dartmouth," he said.

Some college professors question whether the AP curriculum is the best option for the nation's top talent.

While supportive of some AP preparation, College Park chemistry professor John Fourkas advised against students using an AP credit to skip over the introductory class. "A university covers more ground than a high school chemistry course," he said, pointing out that high school labs aren't as sophisticated or as well-equipped as those in college.

Towson University math professor Martha Siegel said AP is an excellent program for a select group. But she has concerns that some students are being rushed through material.

"The program is good; it is just abused," Siegel said.

Broad influence

Some critics believe the College Board, which charges $89 per AP exam, wields too much influence.

Changes that the College Board makes to the AP curriculum can have far-reaching consequences. For example, when it decided evolution should be the cornerstone of biology, the curriculum in some schools changed overnight, as it did when it decided to insert a unit on Islam into the AP government exam.

"We sort of have power that states don't have when their educational policy is dictated by elected officials," Packer said.

The College Board is "big and powerful and has a lot of money, and I think when they come out with a philosophy or strategy of getting AP in everywhere, that can be counterproductive," said Steve Syverson, a board member of the National Association for College Admission Counseling and dean emeritus of admissions at Lawrence University in Appleton, Wis. "Why have we assigned to it such import that it distorts what you do in terms of educating your students?"

In New York, Scarsdale High School decided to buck the trend and no longer offers AP classes. The public school, in an affluent suburb, substituted classes its faculty developed in collaboration with college professors. The resulting Advanced Topics classes are more interdisciplinary in approach and designed to cover less material than an AP class but are still taught at a high level.

"Teachers have the ability to go more in-depth into topics in the curriculum," Scarsdale Principal Kenneth Bonamo said, adding, "We have seen no impact on college placement."

In Baltimore County, a small group of parents is calling for more balance and thoughtfulness in the process of encouraging students to take AP courses. Pease's group isn't seeking an end to AP, but it has met with county school leaders for two years to encourage more high-level classes that aren't AP, as well as more rigorous honors classes.

They have created a "tool kit" designed to help parents and their children understand the demands of AP classes and decide whether a student is ready for them; it is available on the group's Facebook page.

Pease said she is concerned because some county schools have sent College Board form letters to students suggesting they take AP classes based on their PSAT scores. But if students begin to flounder, they don't always get help, she said. In a couple of cases, she said, she helped parents advocate with guidance counselors, but the students weren't allowed to transfer out of the classes.

Dance said he was unaware that any students were not able to transfer out of classes. "We don't want to set students up for failure, but also want to maintain a high bar for all students to strive toward," he said.

But Syverson believes more districts should be focused on offering excellent high school courses rather than having so many students taking an overload of AP.

"So many kids arrive at college psychically and emotionally exhausted these days," he said. "We are creating a generation of very stressed-out 17- and 18-year-olds."

Baltimore Sun reporter Liz Bowie researched this article while she was a Spencer Fellow in education reporting at the Columbia Graduate School of Journalism.