Finland's education system is considered one of the best in the world and contributes to the fact that Finland is one of the world leaders in comparative education tests and in technological innovation. Finland is also considered one of the best societies and economies in the world, along with other countries belonging to the Nordic model. The Finnish education system has unique characteristics of the system compared to other education systems in the world. It has few study hours, few homework, an emphasis on high independence of students and teachers, trust in students and all factors in the system, long-term relationship of teachers with students, and high equality. The education system begins at a young age, and is compulsory until the end of primary education, which ends at the age of 15. At the age of 16-18, students can choose to attend a vocational or theoretical school. The education system is free from kindergarten to university. The OECD conducts PISA tests, which measure the achievement of 15-year-old students in 57 countries, which are rated according to the average score of students in science, math and reading comprehension subjects. In 2007, Finland came in first place (for comparison - Israel came in 39th place).