levels are compulsory, and are commonly referred to as Grunnskole (literally translates to "'base-school"). Elementary and lower secondary school are mandatory for all children aged 6–16. Before 1997, mandatory education in Norway started at the age of 7. Students often have to change school when they enter lower secondary school and almost always have to change school when they enter upper secondary school, as many schools only offer one of the levels. Primary school (Barneskole, Grades 1–7, ages 6–13) In the first year of primary school, students spend most of their time playing educational games and learning social structures, the alphabet, basic addition and subtraction, and basic English skills. In Grades 2-7, they are introduced to mathematics, English, science, religion (focusing not only on Christianity but also on all other religions, their purpose, and their history), aesthetics, and music, complemented by geography, history, and social studies in the fifth grade. No official grades are given at this level. However, the teacher often writes a comment, analysis, and sometimes an unofficial grade on tests. Tests are to be taken home and shown to parents. There is also an introductory test to let the teacher know if the student is above average or is in need of some assistance at school. Lower secondary school (Ungdomsskole, Grades 8–10, ages 13–16) When the students enter lower secondary school, at age 12 or 13, they begin getting grades for their work. Their grades together with their location in the country will determine whether they get accepted to their upper secondary school of choice or not. From eighth grade, students can choose one elective (valgfag) and one language. Typical offered languages are German, French, and Spanish as well as additional English and Norwegian studies. Before the educational reform of August 2006, students could choose a practical elective instead of the languages. Teens born in 1999 and later could once again choose a practical elective known as (arbeidslivsfag) or career studies upon starting lower secondary school, thus getting the option to choose two electives. The electives varies massively between schools, even in the same municipality. A student may take the Grade 10 exam in a particular subject early as long as he or she has been granted an exemption from further instruction in the elementary/middle school curriculum of that subject. In 2009, Norwegian fifteen-year-olds performed better in OECDs Programme for International Student Assessment than other Scandinavian countries,