For the fifth consecutive year, high schools at the Yvonne A. Ewell Townview Center rank No. 1 and No. 2 among the nation’s top 1,900 high schools, according to the Washington Post 2011 Challenge Index, released Sunday.

The Science and Engineering magnet took the No. 1 spot this year, trading places with its sister school, the Talented and Gifted magnet, which this year is ranked No. 2.

Here’s how the Post formulates its rankings:

The formula is simple: Divide the number of Advanced Placement, International Baccalaureate or other college-level tests a school gave in 2010 by the number of graduating seniors. While not a measure of the overall quality of the school, the rating can reveal the level of a high school’s commitment to preparing average students for college.

Other DISD high schools in the index are the Judge Barefoot Sanders Magnet Center for Public Services: Government, Law and Law Enforcement, the School of Business and Management, the School of Health Professions, Booker T. Washington High School for the Performing and Visual Arts, W.T. White High School, Woodrow Wilson High School and Hillcrest High School.