If the 20th century was the epoch of centralization and homogenization in education (which I believe it was), there is perhaps no greater example of that centralizing tendency than the College Board's Advanced Placement (AP) program. Begun in the mid-1950s, over the course of the last fifty years, AP has come to represent one of the gold standards in American education. At some point, it might have been. It no longer is, even though it is what colleges appear to want; it is want high schools want to offer and it is what students want to take and it is what parents want them to take.
The way in which many AP courses are structured places weight mostly on content, which is assessed largely (though not exclusively) through multiple choice exams, rather than on critical thinking, which can be assessed dozens of ways. Furthermore, AP courses are often structured such that no reasonable teacher (and no reasonable student) could ever cope with the expectations of the nationally-normed expectations that the College Board demands of all courses being taught under the AP label. So, in a course where content is king, no school gives teachers and students (or could give teachers and students) the ability to learn effectively. Moreover, even if these courses were given the hundreds and hundreds of hours per school year their content-obsessed curricula demand, students matriculating out of these courses would have mastered a 20th century skill at the expense of urgent, 21st century needs. In this century, knowing content for its own sake will not be the hallmark of learning excellence. Rather, students who will are achieving great success now and will achieve success in the future will be those who, upon learning something, can critique it and apply it in some meaningful way.
Now, the College Board is beginning to institute changes in the AP curriculum. While this is certainly for the better (given that the national political culture fetishizes quantitative data regardless of the party in power), it points to yet another existential crisis for schools and the nation in the 21st century. Our kids, our schools, our teachers, our economy, our job market and our national culture all cry out for meaningful engagement. Will these changes create a culture of rich thinking and purposeful application? It's hard to see how.