The Freie Katholische Schulen Zürich are run by an association of the same name and have taught in the city for about a century, across three school houses: Sumatra, Wiedikon and Kreuzbühl, with the main address at Sumatrastrasse. Around 700 pupils attend, which the cantonal education directorate counts among the largest private rolls in Zurich. Provision runs from the fourth primary year through to the Matura, by way of a Sekundarschule, a vocational secondary track, a tenth school year and a long-form gymnasium. Classes are grouped by level rather than mixed. Teaching is in German and carries a Christian-humanist formation. School fees are set according to family income, deliberately, to keep the school socially mixed, and the association publishes a calculator so families can work out their own figure.