SIS Switzerland School Locations SIS Winterthur Education Levels Bilingual learning on a daily basis, introduced as early as in kindergarten and primary school – education for life. Find out everything you need to know about kindergarten and primary school. Learn more about the continuous education at SIS – one of the major advantages of our bilingual educational concept. The SIS Swiss International School Winterthur offers bilingual education from kindergarten to grade 6 of primary school. On all levels, classes are held both in German and English. However, bilingualism is no prerequisite for admission.