As things now are, the high school teacher finds in the pupils fresh from the grammar schools no foundation of elementary mathematical conceptions outside of arithmetic; no acquaintance with algebraic language; and no accurate knowledge of geometrical forms. As to botany, zoölogy, chemistry, and physics, the minds of pupils entering the high school are ordinarily blank on these subjects. When college professors endeavor to teach chemistry, physics, botany, zoölogy, meteorology, or geology to persons of eighteen or twenty years of age, they discover that in most instances new habits of observing, reflecting, and recording have to be painfully acquired by the students — habits which they should have acquired in early childhood. The college teacher of history finds in like manner that his subject has never taken any serious hold on the minds of pupils fresh from the secondary schools. He finds that they have devoted astonishingly little time to the subject; and that they have acquired no habit of historical investigation, or of the comparative examination of different historical narratives concerning the same periods or events. It is inevitable, therefore, that specialists in any one of the subjects which are pursued in the high schools or colleges should earnestly desire that the minds of young children be stored with some of the elementary facts and principles of their subject; and that all the mental habits, which the adult student will surely need, begin to be formed in the child’s mind before the age of fourteen. It follows, as a matter of course, that all the Conferences except the Conference on Greek, make strong suggestions concerning the programmes of primary and grammar schools,—generally with some reference to the subsequent programmes of secondary schools. They desire important changes in the elementary grades; and the changes recommended are all in the direction of increasing simultaneously the interest and the substantial training quality of primary and grammar school studies.
If anyone feels dismayed at the number and variety of the subjects to be opened to children of tender age, let him observe that while these nine Conferences desire each their own subject to be brought into the courses of elementary schools, they all agree that these different subjects should be correlated and associated one with another by the programme and by the actual teaching. If the nine Conferences had sat all together as a single body, instead of sitting as detached and even isolated bodies, they could not have more forcibly expressed their conviction that every subject recommended for introduction into elementary and secondary schools should help every other; and that the teacher of each single subject should feel responsible for the advancement of the pupils in all subjects, and should distinctly contribute to this advancement.
—from the main report of the Committee of Ten on standardizing the U.S. high school curriculum, 1892 (emphasis added)