Sometimes parents complain to Charles Thomas that he is asking too much. Their children aren’t sleeping, their grades are slipping or they just can’t handle the workload of an Advanced Placement class.

The principal of Crossland High School in Prince George’s County gives a simple reply.

“All these demands are going to be made when your child gets to college,” Thomas tells them. “If they can’t do this work, they are not going to be prepared.”

For seven years, Thomas has made expansion of the AP program a centerpiece of his efforts to transform what he thought was an underperforming school into a factory for molding college-ready students. He’s an AP evangelist.

Each year, Crossland produces roughly 300 graduates. In 1999, seven AP tests were given at the school. A decade later, there were almost 700.

“Ridiculous, isn’t it?” Thomas laughs.

Thomas holds the view that student achievement will grow in tandem with rising standards. He reels off statistics to prove the point: 78 percent of the school’s seniors passed the state High School Assessment in English in 2010, compared with 22 percent in 2004. Three-quarters passed the algebra exam, compared with 15 percent in 2004.

Still, his students typically fail the AP exams. Only 3 percent of Crossland test-takers earned a passing grade last year of 3 or better on the 5-point scale. Thomas tries not to sweat that. Nearly half of the school’s students qualify for free or reduced-price lunch, a common measure of poverty. He says there is inherent value in forming a stronger academic foundation, particularly for students from low-income families, while building their confidence to seek a college degree.

About 10 percent of graduates were accepted to four-year colleges when he came in 2004. This year, Thomas says, the share is 80 percent.

Parents need not hunt on the Internet to find the numbers. The school’s electronic billboard on Temple Hills Road boasts them for all to see.

Posted in quiet hallways are bar graphs, bulletin boards and banners praising the school’s improvement. One wall shows where last year’s graduates went to college, ranging from the local community college to the University of Pennsylvania.

Thomas says the mood was different in 2004. Hallways were filled with loud, sometimes vulgar conversations, and some teachers had spotty attendance records.

Thomas banned profanity in the building and spent more time observing teachers. He called for those who were excessively late or absent to explain themselves, a tactic he said contributed to 80 percent turnover in teaching staff in his first three years.

The principal then sought to raise standards. He instituted the International Baccalaureate program for the top 5 percent of students. And he opened up AP classes to all students who could read at grade level.

He says he took social conditions into account. Many of his students lacked books at home, had never taken a summer vacation to a foreign place or had a caregiver who had never been to college.

“The fact that they are still reading at grade level, when you know they didn’t have all those things, means there is an untapped intelligence there,” Thomas said. “So it’s our job to flip the switch within them and help them to grow and excel.”

Now, most seniors graduate with five AP classes under their belt, from a dozen subjects, such as Spanish, psychology, calculus, human geography and English literature. Many said they were thankful for the push.

“I considered myself a poet, but I didn’t know how to explain what I was writing until we started going over all these terms in AP Lit,” said 18-year-old Ashley Talley, who will probably attend Shaw University in North Carolina. “At first, I thought I couldn’t handle the class, but I needed to take it.”

Talley’s teacher was Kisha Woods, who is known for giving students a heavy workload. On the final day of classes for seniors, Woods gave the principal a report about her farewell to her students.

“They were boo-hooing all over the place,” she said. No one ever pushed us as hard as you did, they told her. To which she responded:

“Just wait until you get to college.”