The prominence of sport in American secondary school curriculum owes much to 19th-century child development theories, the most prominent of which, Von Baer's Law, held that youth passed through the same developmental gradations ontogenetically that the human race passed through phylogenetically; youth repeated in their development approximately…

Broken free of any semblance of family control or community restraints, thousands of American youth roamed entirely at will throughout the cities of 19th-century America and supported themselves alternately from the legitimate street trades and from outright thievery. The invention of modern adolescence was partially a response to this neglected…