Jacques Barzun was one of the great humanities scholars of the 20th century. Among his many achievements were several classic books on education and teaching, books such as Teacher in America (1945) and Begin Here: The Forgotten Conditions of Teaching and Learning (1991).
In Begin Here, Barzun discusses where educational nonsense comes from by identifying three common but mistaken assumptions about teaching children.
The first is ignoring the fact that schooling involves teaching in groups:
Thus a plan that might be workable if applied by a gifted tutor to a single child living continuously in the same house becomes nonsense when proposed for classroom instruction in an institution designed for hundreds or a national system designed for millions.
The second involves assuming that a method or technique used by one particularly talented teacher is going to work if it is used on a mass scale by other teachers not so talented.
Finally, there is the idea that we can, with profit, replace academics with “real life” activities:
[N]onsense is at the heart of those proposals that would replace definable subject matter with vague activities copied from “life” or with courses organized around “problems” or “attitudes.” The attempt to inculcate directly, as a subject of instruction, any set of personal, social, or political virtues is either indoctrination or foolery. In both cases, it is something other than schooling.
And don’t miss his magisterial history of modern culture, From Dawn to Decadence: 500 Years of Western Cultural Life.