This explains why coverage in the mainstream news media is liberal. The New York Times is simply more interested in furthering its social ideals than in reporting news. That is why, to cite just one recent example, the newspaper featured such poor reporting about the Duke lacrosse players who were falsely charged with raping a black woman. The facts suggested the district attorney had trumped up the charges, but The New York Times was less interested in the facts than in portraying rich white Duke athletes as racists.
With regard to education, the same change of purpose has occurred. Until the left took over education, the primary purpose of a teacher was to teach, and to do so as truthfully and apolitically as possible. Today, the primary purpose for very many high school teachers and college professors on the left is to influence students. That is why so many high schools show students Al Gore's "An Inconvenient Truth" (and show nothing that contradicts his thesis). It is more important to influence young people to fight global warming than it is to teach them.
The same holds true for textbooks. Until the left took over education, textbooks were largely chosen on the basis of their clarity and historical accuracy. But for leftist educators, a vital goal of American history texts is to make minority students feel good about themselves. Thus, history can be distorted so as to give as much attention to minorities and women -- no matter how much less significant their actual roles in American history -- as to white men, who constitute the great majority of the primary figures who shaped American history.
And the situation in universities is even worse. Entire departments -- English, sociology, political science, women's studies and African American studies, to name a few -- have become leftist laboratories. Their commitment to actual, let alone objective, teaching is minimal. A student is no longer supposed to leave an American university well educated in Western civilization -- the primary purpose of a university education throughout American history -- but committed to left-wing notions of social justice, economic equality, environmentalism, opposition to American exceptionalism, self-identification as a world citizen rather than as primarily an American, and the like.
Merely teaching is as unimportant to most left-wing teachers and professors as is mere reporting of the news for left-wing journalists or mere rendering of justice to most liberal judges. They regard their professions not as ends but as means -- to higher, leftist ends.