Nineteen public high schools in South Carolina are on the 2008 Newsweek magazine / Washington Post "Challenge Index," an annual survey that measures rigorous course offerings and how all students perform in those classes.

The index uses a formula that divides the number of advanced placement and similar tests that can lead to college credit by the number of students who graduated (a year ago).

The system is designed "to recognize schools that challenge average students and not magnet or charter schools that draw only the best students in their areas," according to Newsweek's Website. This year's index includes the names of 1,358 public high schools, but does not include the names of any schools that have an average SAT score topping 1300 or an AP score of 29 or higher.

One Midlands' high school, Spring Valley, fell out of the rankings. Dreher High School was added to the new rankings .

South Carolina had 12 schools on the index in 2003, 13 on the list in 2005, and 23 ranked in 2006. Greenville County has had the largest number of schools listed each year.