At the dawn of the 20th century, educators were faced with a huge influx of children from foreign-immigrant families and families coming to the cities from farmlands. Educators turned to America’s signature dynamo at the time, the factory, after which they modeled America’s comprehensive secondary schools.
Critically important to public-school designers at the time was judicious use of tax dollars. Spending public money on other people’s children was, and still is, a dicey thing to do. Educators could not justify spending money on frills like the leafy campuses, broad course-offerings or personal attention that characterized private schools for the well-to-do. Inefficiency was not an option, because it would threaten the whole project of educating a democratic citizenry.
The solution, as expressed by Ellwood P. Cubberly, an early 20th-century historian of education, was to create “scientific” schools that would be “factories in which the raw materials [children] are to be shaped and fashioned into products to meet the various demands of life.”
High schools and junior highs — the latter were invented around 1910 — put students on a self-propelled conveyer belt that moves from classroom to classroom to get a rivet of English, a bolt-tightening of math, and so forth. To improve efficiency, schools sorted students into “tracks,” grouped according to their economic prospects — college, general, vocational. The final product at the end of the line was an educated student, which in today’s terms means acceptable test scores.
Much of slate mining in the United States occurred in the Northeast, places such as Maine, Vermont, Pennsylvania, and a bit further to the South in Virginia. As Americans began to expand to the West, the new railroads were able to bring slate for blackboards from these states to schools across the Great Plains and prairie lands by the 1840's. No matter where Americans went, slate followed for use in public schools.