According to Zinn, what was the primary purpose of a public school education during the Gilded Age?

According to Zinn, the primary purpose of a public school education during the Gilded Age was to train skilled and semi-skilled workers for the new age of industry.
The rise of public school education coincided with the proliferation of new colleges that were funded by millionaires. For example, Rockefeller founded the University of Chicago, and millionaires such as Cornelius Vanderbilt, Ezra Cornell, James Duke, and Leland Stanford founded universities in their name. Today, Vanderbilt, Duke, and Stanford Universities are known to us all.
During the Gilded Age, however, these universities (like the public schools) were created to train the next generation of docile, obedient workers for the industrial age. The schools graduated students who would then attend these colleges. The college graduates invariably took their places as nurses, doctors, engineers, politicians, and teachers, fulfilling their societal roles without question. There was little room for dissent in the public school institutions during the Gilded Age.
Mill owners especially favored workers who were properly indoctrinated in the schools they attended. They believed that such workers were less likely to participate in strikes and demonstrations.