Countries with higher student achievement in 1960, as measured by test scores on an international exam, had higher rates of economic growth between 1960 to 2000. Harvard economist and blogger Greg Mankiw recently called it the "correlation of the day":

http://gregmankiw.blogspot.com/2012/05/correlation-of-day.html

The full OECD report, by economists Eric Hanushek and Ludger Woessmann, on the relationship between student achievement and economics growth can be found here:

http://hanushek.stanford.edu/sites/default/files/publications/Hanushek+Woessmann 2010 OECD_0.pdf

A recent Wall Street Journal piece by Hanushek and former U.S. Secretary of State Georgia Schultz on these findings can be found here (gated):
 
http://online.wsj.com/article/SB10001424052702303513404577356422025164482.html