The school system in Australia is different from the school system in The Netherlands. At the age of 5 or 6 years old, children start primary education. After six or seven years of primary School they start Secondary Education which is compulsory up up to the age of 15. The final two years of high school, they choose a smaller number of subjects to specialize in.
Children may leave school after age 15 but must complete Year 10 to get their School Certificate.