The Greek educational system is mainly divided into three levels: primary, secondary and tertiary, with an additional post-secondary level providing vocational training. Primary education is divided into kindergarten lasting one or two years, and primary school spanning six years (ages 6 to 12). Secondary education comprises two stages: Gymnasio (variously translated as Middle or Junior High School), a compulsory three-year school, after which students can attend Lykeion (an academically oriented high school) or Vocational training. Higher Tertiary education is provided by Universities and Polytechnics, Technological Educational Institutes (T.E.I., 1983 ~ present) and Academies which primarily cater for the military and the clergy. Undergraduate courses typically last 4 years (5 in polytechnics and some technical/art schools, and 6 in medical schools), postgraduate (MSc level) courses last from 1 to 2 years and doctorates (PhD level) from 3 to 6 years.