CAMDEN — The number of students in Delaware who take and pass Advanced Placement classes continues to grow, according to new data from the College Board.

The number of public high school graduates who took an AP exam sometime during high school has doubled over the last 10 years.

In the graduating class of 2014, 18 percent of students passed at least one AP test with a score of 3 or better on a five point scale — up from 10.6 percent a decade earlier.

Gov. Jack Markell visited Caesar Rodney High School on Thursday to announce the gains.

Speaking to Lisa Kane’s AP Biology class he commended the students, who are set to take the AP exam next month, for challenging themselves.

“The surefire way of making sure you’ve got this strong trajectory to success is to continue to take the most challenging classes when you’re in high school,” he told them.

The College Board offers AP classes and tests in 34 different subjects; students who score at least 3 may be eligible to receive college credit.

At Caesar Rodney, students can choose from 22 AP courses.

“I think its our charge to make sure that our students are prepared for life beyond Caesar Rodney High School,” principal Dr. Sherry Kijowski said.

“...there are lots of avenues, so that a student can find their passion, find out what it is that they want to do, and then go on from there. I think the AP is just one piece from that.”

When Gov. Markell asked the students in Ms. Kane’s class about their course load, almost all of them said they were enrolled in multiple AP classes — one student was taking seven.

Student Kate Holden, who was getting ready Thursday for a lab on transpiration, the process through which plants produce water vapor, said biology is one of her favorite subjects. She added AP English to her schedule, too, because she wanted to become a better writer.

Kate said she values the classes more for the experience they offer than the recognition.

“It’s more just preparation for the actual classes I take (in college),” she said.

“I think the kids like to challenge themselves, because they get no rewards,” Ms. Kane said.

“Our classes are not weighted, so they are left to take these classes because they like to challenge themselves. They want to build their resume for the colleges they’re going to.”

Across the state, students made particularly strong gains in biology over the past three years.

In 2012, 440 graduates took the biology exam and 38.9 percent scored three or higher; among 2014 graduates, 615 took the test and 60.7 percent passed.

And in Ms. Kane’s classroom, 84 percent of her students passed the test in 2014.

Data released Thursday also showed strong statewide gains in the Calculus AB test, the World History exam and the AP English Literature test.

At Caesar Rodney, assistant principal Daniel Lopez said that AP classes teach students rigor, discipline and organization.

“How do you manage all of this — in a world where nobody is standing over you telling you how to manage it?” he said, “I think it teaches you how to really manage that material and really how to...just analyze.”

College readiness was a central part of the Delaware’s plan for the federal Race to the Top grant competition.

When the state won the grant in 2010, officials used part the money to support the growth of advanced placement classes and encourage students to enroll in them.

One of the state’s focuses was AP Biology; officials even used grant funds to make teaching resources available online.

Gov. Markell said that tough classes are important because more jobs than ever require education after college.

“My guess is for most of you when you get to college, you’ll find that based on the fact that you took these AP classes now you are better prepared than you otherwise would have been,” he said.

Along with advanced placement gains, the number of student taking dual enrollment classes, college-level classes taken by high school students to also earn college credit, more than doubled between 2013 and 2014.

Gov. Markell also announced this week that the state’s “Getting to Zero” initiative succeeded for the second year in getting every “college-ready” student, identified based on their score of at least 1550 out of 2400 on the SAT, to apply to college.