Chris O'Donnell published a post that excerpts some thoughts originally published on this post by David Friedman:
One of the assumptions built into the conventional version of K-12 schooling, private and public, is that there is some subset of human knowledge, large enough to occupy most of twelve years of school, that everyone needs to know. That assumption is false. There is a very short list of skills-reading, writing or typing, and simple arithmetic are the only ones that occur to me-that almost everyone will find worth learning.
I’ve go to agree with Chris in that I really like the shorter explanation:
I sometimes describe it as throwing books at them and seeing which ones stick.