Once children leave primary school (bassisschool), they enter secondary education which generally continues until the age of 16 - 18, depending on the type of education chosen. All secondary schools start with a basic curriculum. Every student takes a wide variety of classes that are more or less the same regardless of which school is attended.
In the Netherlands, there are different levels of secondary education:
Lower secondary professional education (Voorbereidend Middelbaar Beroepsonderwijs - VMBO)
Children are prepared for a practical internship followed by employment or vocational education. A VMBO course generally takes four years.
General senior secondary education (Hoger Algemeen Voortgezet Onderwijs - HAVO)
This course takes five years and prepares the child for Higher Vocational Education/College/University of Applied Sciences (HBO).
Pre-university education (Voorbereidend Wetenschappelijk Onderwijs - VWO)
This course takes six years and is the admission level for universities.
The Ministry of Education, culture and Science has a dedicated website listing all primary and secondary schools.