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 the education levels on offer at SIS Winterthur. Learn more about the continuous education from preschool to college offered 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.