Experience Workshop introduced the Poly-Universe toolkit in Helsinki’s mathematics high school in Maunula on 13.11.2021. The occasion was the school’s yearly mathematics festival called HARPPI, full of exciting mathematics-related games, activities and toolkits. HARPPI however is more than an event, it is the name of a national mathematics development project funded by the Finnish ministry of education and culture. The festival was visited by appr. four hundred students and their teachers during the day.