Success on the AP exams had eluded Destiny — and most of her Woodlawn classmates. Her highest score on the four exams she had taken so far was a 2, in English. The College Board grades on a scale of 1 to 5, with 5 being the equivalent of an A to B+ in an introductory college course. A score of 3 is needed to pass.

"There is a discouraging factor, but for me I haven't been taught to give up on anything so it makes me try to study harder and do things differently," said Destiny, who is soft-spoken and serious. Her face is framed by red glasses, and her long fingers sometimes float through the air as she talks. A sprinter on Woodlawn's track and field team, she has the lithe body of a runner.

When Destiny got the first reading assignment, in a textbook designed for college introductory biology classes, she dug in. She had read hard texts in other AP classes, but this was far more difficult. The important parts weren't bolded, so she did not know where to focus her attention. "OK, it is going to be a very long year," she told herself.

In the first few days of school, Patterson noticed that his new class had a keen interest in biology, a great sign. But he knew challenges lay ahead, the greatest of which would be to teach his students — experts at getting good grades by spitting back basic material — to analyze complex information.

Patterson, a young teacher with a no-nonsense demeanor, tried different approaches to reach his students. In one class, he threw himself into the story of Phineas Gage, a railroad worker who survived an accident that sent an iron rod through his skull but that left his personality changed. He wanted students to understand what Gage's experience taught scientists about the frontal lobe. They listened intently and then used scalpels to gingerly poke preserved sheep brains to identify the area damaged in Gage's accident.

But on another day his students were tentative and barely spoke as they tried to do an experiment. The goal was to determine whether the rate of respiration in plants or animals was affected by temperature, using crickets in big glass jars and seeds that had been germinating.

Seeing the uncertainty on his students' faces, he tried to give direction without dictating the next steps. But he was left asking the most basic of questions: "How will you divide up the work?" and "You all are writing this down as you go, aren't you?"

When Patterson gave the first test, Destiny studied hard and thought she nailed it. She was shocked by the result: a C.

"It really scared me," she said.

AP expands

AP has a broad reach in Maryland and across the nation as students try to get a jump on college. Two million students now take the exams nationwide. And in Maryland, the number of students sitting for an exam grew from just 8,447 students in 1990 to 55,000 students last year.

Created in 1954, AP was designed for elite students from the best high schools who were trying to skip introductory college classes by taking a tough exam.

Every year since the first exams were given to 543 students, AP has expanded to more high schools and more students, but the leap from well-known to widely used came during the past decade. In 2006, President George W. Bush set a goal of tripling the number of students taking AP classes in science and math within five years.

States embraced the movement, and then-Maryland schools Superintendent Nancy S. Grasmick pushed to expand the courses to underserved groups. "We had whole [school districts] where we didn't have AP offerings," she recalled.

With the help of the College Board, she created a color-coded map highlighting the districts offering the most and fewest AP courses. At least once a year she showed local superintendents which district was winning the AP race.

The colors on the Maryland map quickly changed, until nearly every school offered AP.

Part of the expansion has come at top schools like Dulaney High, where students last year were crammed into two slightly worn-looking AP biology classrooms that lacked air-conditioning but had a wealth of lab supplies. In one were 29 seniors, seasoned veterans of AP, having taken biology, physics, chemistry and high-level math.

Martin Stranathan's students ranged from blond prepsters to native Hindi speakers, but all viewed themselves in a competition for the top universities. They enrolled in four to six AP classes and aimed for a 5 on the exams.

"We are a community," said Jiaxi "Josh" Wei, a Chinese immigrant. "If we don't work hard we are going to be left behind."

Like Destiny, Josh wanted a career in medicine, but he understood more clearly what it would take. He came from a line of doctors. His father does medical research and his mother holds a doctorate. When he entered high school, his parents told him they expected him to work hard enough to get into a good college.