QUOTE Although less than 17% of the US population has blue eyes, all but six US presidents have.
Eye color might be a factor in the success of a US presidential candidate. Less than 17% of people in the United States have blue eyes, but all but six of the first 44 presidents are believed to have had blue or gray eyes.
Only five -- Richard Nixon, Lyndon B. Johnson, Chester A. Arthur, Andrew Johnson and John Quincy Adams -- had brown eyes. Nobody is quite sure as to why this is, although some people have suggested that blue eyes might be considered more attractive than brown, black or hazel eyes. It is important to note that there is a wide range of eye colors, and when it comes to presidents who served before color photography, their exact eye colors are not easy to determine. UNQUOTE http://www.wisegeek.com/how-many-us-presidents-had-brown-eyes.htm?m
What this may have to do with the effective teaching or learning of math, I would not know - but I'm certain some kind of linkage could be found if we're persistent enough.
GSC - - for whatever it is worth ("Still Shoveling Away, Anyway!")