Can you explain the school system in US to an european that knows nothing about it?
user
Americans go to school for 12 years (grades). At age 6, they start primary (or elementary) school. After this, they move on to secondary school which consists of 2 programs. The first program is middle school (a.k.a. junior high school, or just junior high). The second program is high school.
After graduating high school (12th grade), a diploma is granted and the students can move on to higher education as either college or university.

Does that explain it sufficiently?
assistant