A standardized education on the Roman model was only of use for the upper crust of society and the extremely intelligent. For the rest, a system of informally learning crafts dominated a majority of the population.
Beginning from a young age, children whose parents could afford would be assigned to a craftsman - carpenter, smith, shipbuilder, etc. An apprentice would remain with a master until his teacher had deemed him sufficiently knowledgeable to go out on his own. He would then be given the status of journeyman.