Education in Switzerland is very diverse because the constitution of Switzerland delegates the authority for the school system to the cantons. There are both public and private schools, including many private international schools. The minimum age for primary school is about six years in all cantons, but most cantons provide a free "children's school" starting at four or five years old. Primary school continues until grade four, five or six, depending on the school. Traditionally, the first foreign language in school was always one of the other national languages, although recently (2000) English was introduced first in a few cantons.