Before 1900 most children learned at home and out in the real world.
But in 1837, the State of Massachusetts formed the first state board of education, with Horace Mann as its secretary. Mann believed that everyone was entitled to the same content in education. Returning from a research trip to Germany in 1848, Mann lobbied heavily to have the Prussian model adopted. He quickly set about establishing a statewide system of “common schools," staffed by professionally trained teachers. His ideas quickly gained momentum and by 1852 Massachusetts passed a compulsory attendance law.
It's surprising how few people, including teachers and administrators, know the real history and reasons behind the compulsory school system and the real reasons are far more sinister that you'd imagine.
Here's a short scene from the documentary Class Dismissed that highlights some of those reasons.