Students may choose what level of school to attend, there are three types of "scuola secondaria di secondo grado" that range from the academic to the vocational. The vast majority of students attend the "istituto". All students follow a common course of core subjects during the first two years augmented by subjects from their elected specialism. Programs of study are generally introduced at national level. Currently, most secondary schools provide some common structure and core subjects (such as Italian language and literature, history, geography, philosophy, mathematics, physics, biology, chemistry, one or more foreign language and physical education), while other topics are specific to one type of establishment (i.e. Ancient Greek and Latin in the "Liceo Classico"; economy and law in a "istituto tecnico economico"; scenography and music in a "liceo artistico"). In 2013, the Programme for International Student Assessment, coordinated by the Organisation for Economic Co-operation and Development (OECD), ranked the Italian secondary education as the 21st in the world, higher than the United States, around the OECD average, and observes a gap between results in Northern Italian schools, which performed significantly better than the national average (among the best in the world in some subjects), and Southern Italian schools, that had, on average, somewhat poorer results. Moreover, students in state-owned schools perform better than students in private schools. A typical Italian student is age 19 when they enter university, while in other countries 18 is the more common age. The education offered by a "liceo" (lyceum) is mostly academic. Individual lyceums will cover the core subjects and specialise in specific fields of study; this may be the humanities, science, or art. The principal focus is to prepare students for university and higher education. Types of liceo include: Historically:  The education given in an "istituto tecnico" (technical) offers both a wide theoretical education and a highly qualified technical specialization in a specific field of studies (e.g.: economy, humanities, administration, law, accountancy, tourism, information technology), often integrated with a three-six months internship in a company, association or university, during the fifth and last year of study. Types of istituto tecnico include:  The "istituto professionale" (literally:professional institute) is a vocational college, specifically structured for practical activities, with the aim to facilitate the direct entry of the pupil to the labour market (engineering, agriculture, gastronomy, technical assistance, handicrafts).