Luxembourg's education system is trilingual: the first years of primary school are in Luxembourgish, before changing to German, while secondary school, the language of instruction changes to French. However, as proficiency in all three languages is required for graduation from secondary school, half the students leave school without a certified qualification, with the children of immigrants being particularly disadvantaged. The University of Luxembourg is the only university in Luxembourg. There are several international schools in Luxembourg. The number is impressive taking the population size of the country into consideration.