SIS Switzerland School Locations SIS Pfäffikon-Schwyz Open House Experience our International School Atmosphere. We cordially invite you and your children to visit SIS Pfäffikon-Schwyz on Thursday, 3 November 2022 between 9 a.m. and 12 noon. Come and get an insight into the bilingual day-to-day school life held in German and English. Experience our international school atmosphere and observe lessons in our preschool, primary school and secondary school. The school principal will be there to answer all of your questions. We look forward to your visit!