Steve Sailer has a new blog entry, “The inanity of teacher training,” consisting largely of a lengthy quote from Heather MacDonald, that nicely illustrates part of the problem with the current “educational system” in the USA. It is also worth reading MacDonald’s essay in its entirety.
To pursue this in greater historical detail, see Kliebard's classic The Struggle for the American Curriculum, 1893-1958, which manages to be both scholarly and remarkably readable.
However, I think that Sailer and MacDonald have only identified part of the problem: a century ago, many American parents did oppose the content-free curriculum.
But, today, this is actually what a large number of American parents want for their children. A "content-full" curriculum leads to kids who are "nerds," and many parents would rather have their children grow up to be illiterates than nerds.
Advocating knowledge for its own sake is a subversive stance in contemporary America.