By Mary Beth Marklein, USA Today, September 10, 2009

Researchers studying how to improve graduation rates at public colleges and universities have come up with a surprising and counter-intuitive finding: Many students may fail to complete a bachelor's degree not because the work is too hard — but because they're not challenged enough.

http://www.usatoday.com/news/education/2009-09-09-college-graduation-academic_N.htm