In the context of the priority given to social development in the early postcolonial years, rapid educational development took place in Sri Lanka from the 1940s to the mid-1960s. Free primary, secondary, and tertiary education was introduced in 1945, accompanied by free health services and subsidized food policy at about the same time. Central schools were established between 1940 and 1947 to extend secondary education to rural areas. The mother tongue (Sinhala or Tamil) became the medium of instruction to relevant groups in primary and secondary schools. The majority of schools were nationalized in 1961, at which time only 2% of all students were enrolled in private schools. There was a rapid expansion in secondary and higher education between the late 1950s and mid-1960s.