I can feel the eyes of people who have yet to read this glazing over.
Let me tell you a story. I grew up in the San Francisco Bay Area. When I was in the 7th grade, I was helping a teacher set up some maps before class (I had arrived a couple minutes early after lunch). During the conversation she said the following:
"Most of your classmates cannot find the United States on a World map, California on a US map or San Francisco on a California map."
That day in class, she was proven correct when at least half of the people in the class failed at the above tasks.
What I am trying to say is that seems that seem so completely common sense or common knowledge to those with even the most average of intelligence and education, may be completely beyond others.
I know some very intelligent and well-educated people who I would be willing to bet a lot of money do not understand why we have a leap day (And many of those individuals are Jewish and have been told of the leap month in the Hebrew Calendar their whole life, too).
MotionMan