A Mathematician's Lament

This 25 page article by NYC mathematics teacher Paul Lockhart (written in 2002) is well worth the time it takes to read it.
You will never think about math the same way again. You may feel bitter about the lies you were fed during your math education (the beauty of mathematics you never knew about, the fact that math is a creative endeavour; like painting and music it is an art, and is about ideas). Still, it is never too late to fall in love with the subject, or at least to gain an understanding of what math is really about.
Read the essay at Delvin's Angle;
http://www.maa.org/devlin/devlin_03_08.html

What others have said:

"The Lockhart piece, available as a 25 page pdf, is one of the most insightful arguments about what is wrong with how we generally teach mathematics in this country and what we could be doing instead. It should be required reading for anyone connected in any way with the teaching and learning of mathematics or who wants to have a truly informed perspective on what makes sense for teachers and kids to be doing in mathematics classrooms."
M. P. Goldenburg

Rational Mathematics Education " An essay you must read."
http://rationalmathed.blogspot.com/