More high school students in Fairfax County took and passed college-level Advanced Placement exams in 2009 than in years past.

Nearly 15,000 students sat for nearly 30,000 grueling exams in the spring in subjects from computer science to European history, up from just over 14,000 students in 2008. About 55,000 high school students fill the county’s classrooms, but the tests are taken most widely among upperclassmen.