Advanced learning was concentrated in a few monastic and cathedral schools in 1000. Later in 1300 the leading institutions of advanced learning were the universities, of which there were perhaps twenty. At a humbler level, a growing network of lower schools, often called grammar schools, taught the basics of literacy in Latin to the children of those willing to pay. In those three centuries, there were massive increases in the number of students and teachers. There were also significant changes in the organisation and curricula of the schools. Basic literacy in Latin and in the many vernacular languages increased dramatically between 1000 and 1300, especially in urban areas. Bailiffs, clerks, merchants and government functionaries, indeed anyone who needed to read a contract, balance a ledger, or issue or carry out a written order had to be literate, which meant reading and writing in Latin. The development of medieval schools was organic, with new departures growing out of existing institutions.