@thor
Basisschool, 0-8.
Middelbare school, the grades reset. Because the middelbare school have their own levels as well, which are preludes for the LBO/MBO/HBO/Universiteit. They each also differ in amount of years needed to finish it. In those levels you already choose the direction you're interested in so you get the courses fitting your direction.

Once you finish the middelbare school, you continue on the job education (vocation) or universiteit.