Stranathan had many students like Josh. He knew that when the bell rang at 7:50 a.m. everyone would be seated and ready to go. No one wandered in late, as they would at Woodlawn, and nearly everyone kept up with the reading — about 13 pages a night of dry, difficult material.

Stranathan, a soft-spoken, slightly rumpled teacher, focused on asking questions and allowing students to discuss issues, instead of using lectures and PowerPoint presentations.

"If you can talk your way through the content, then you will understand it," he said.

During the hour-and-a-half-long class, they discussed the causes of hypo- and hyperthyroidism, conditions in which the thyroid gland produces too much or not enough of a hormone, and the endocrine and exocrine systems, glands that secrete hormones into the blood system or ducts.

"He makes us solve the question ourselves, never just sit there and take notes," said Josh.

While the College Board defines what topics will be covered on the exam, it does not give teachers a specific curriculum. So they must create their own lessons and decide how far to push their students.

The contrasts between the AP biology classrooms ran deep. While Dulaney students pored over the textbook, Woodlawn students looked for shortcuts. Patterson assigned the same reading that Stranathan did and required students to answer study questions to ensure that they were doing the assignments. But some students procrastinated, never reading the entire text and just looking up answers online, according to Patterson and students.

Destiny felt she needed two to three hours a night to read the textbook carefully, and she didn't have time to do that. She worked three days a week until 10 p.m. and all day Saturday when she wasn't playing sports. So she focused on skimming certain sections and concentrating on others. She got a B in the first quarter, falling short of her own expectations.

Stranathan expected nearly all of his students to pass the exam, so his goal was to deepen their ability to think and analyze. Patterson knew his odds of success weren't good — only 7 percent of Woodlawn students enrolled in an AP class had passed the exam the year before — but he tried to keep expectations high.

Critics have charged that the AP label is not consistently applied at all schools. Many students at low-performing schools are ill-prepared for the courses, said Kristin Klopfenstein, executive director for the Education Innovation Institute at the University of Northern Colorado.

"A common response to the access problem was to helicopter-drop AP courses into disadvantaged high schools," she said. "The thinking was that this would improve these schools by setting high expectations."

Calling a class AP when it's not taught at a college level can leave students with the misperception that they are prepared to take college classes when they are not. Often when students arrive at college, they must take a remedial class in math or English before they go on to credit-bearing college classes in the subject. No Maryland data are available specifically on AP students and remediation.

For instance, 31 percent of entering freshmen at four-year public colleges in Maryland need remediation, including 41 percent of students at Frostburg University and 79 percent at Morgan State University. Those who have a rough start can end up never graduating.

Nationwide, slightly more than half of students will graduate from the four-year college where they started, according to the National Center for Education Statistics. The financial and personal cost to those who don't finish is serious: Many will leave with debt and no degree.

Shrinking numbers

The dark days of winter brought a depressing dose of reality in some AP classrooms.

Some students who started out in Patterson's biology class disappeared from the seats beside Destiny.

It was far worse in Adam Sutton's AP economics class at Woodlawn. From 50 students in September, Sutton was down to 27. His students drifted away one by one, transferring to easier classes.

"There are select students at Woodlawn capable of meeting AP standards, but many have skills that are not up to par; I refuse to lie to my students about where they are with regards to meeting AP standards," Sutton said. "They need to meet my expectations — mine won't fall to meet theirs."

Woodlawn doesn't have a critical mass of top students who have grown up in a culture of high achievement, teachers said. Too often, students sail through the gifted and honors classes with top grades by showing up and following directions. And when they look around the school, they see themselves as the best students.