The Italian educational system is strongly centralized. It consists of nursery school from ages 3 to 5, primary school from ages 6 to 11, lower secondary school (middle school) from ages 11 to 14, and upper secondary school from ages 14 to 19. Compulsory education ends at age 15 after middle school. Upper secondary school includes both academic high schools focusing on subjects like humanities, sciences, languages, and arts as well as vocational and technical schools. High schools last 5 years and conclude with a national exam. Italian schools group students into class cohorts that stay together for lessons taught by rotating teachers for several years.