Children usually start in kindergarten or grade one at the age of five or six and go up one grade each year until reaching grade 12 at the age of 17. Occasionally a student must repeat a grade because of prolonged absence or low marks, although this is rare. The 12 years following the kindergarten year are usually organised under what is known as the ‘6-3-3 plan’ where grades 1 to 6 are in elementary (primary) school, grades 7 to 9 in junior high or middle school and grades 10 to 12 in a (senior) high school.