Isn't it natural for children to be divided by age in school?
The fact is, however, that most American schools were ungraded until the second half of the nineteenth century, the graded school having been introduced in the United States in 1848, when the Quincy Grammar School in Boston, Massachusetts, opened its doors.
A number of educators, impressed with the graded schools they had seen in Germany, had been proposing adoption of the technique in this country.
The Quincy School was the first built for that purpose; it contained twelve rooms of equal size, four to a floor, in which a teacher and some fifty-five children would meet for a year at a time. The men who created the school predicted that it would set the pattern of American schooling for another fifty years. Their estimate was clearly conservative.
Charles Silberman, Crisis in the Classroom: The Remaking of American Education (New York: Random House, 1970) p. 166 (emphasis added). I first read this book as a ninth grader (who had earlier skipped sixth grade) in 1972, soon after I had read John Holt's How Children Fail. This was heady stuff for someone as unhappy with school as I was and undoubtedly accounts for my lifelong interest in education reform.
Silberman goes on to quote a critic of age-grading: It is constructed upon the assumption that a group of minds can be marshalled and controlled in growth in exactly the same manner that a military officer marshalls and directs the bodily movements of a company of soldiers. In solid, unbreakable phalanx the class is supposed to move through all the grades, keeping in locked step. This locked step is set by the 'average' pupil--an algebraic myth born of inanimate figures and an addled pedagogy.
The class system does injury to the rapid and quick-thinking pupils, because these must shackle their stride to keep pace with the mythical average. But the class system does a greater injury to the large number who make slower progress than the rate of the mythical average pupil . . . They are foredoomed to failure before they begin....