The Freudenthal Institute is part of Utrecht University in the Netherlands and conducts research on math education. The goals are "to understand and improve the teaching of arithmetic and mathematics at all levels, but particularly in kindergarten, primary, secondary and vocational education." The Freudenthal Institute has developed a theoretical approach known as Realistic Mathematics Education, which is based on the idea that "education should guide the students towards using opportunities to reinvent mathematics by doing it themselves." Through a collaboration with the Wisconsin Center for Education Research (WCER), at the University Wisconsin-Madison, the Freudenthal Institute - USA(FiUS) focuses on: Supporting teacher development of classroom assessment, designing comparative achievement studies, developing curricula and materials for students, teachers and parents, building leadership capacity in school districts through professional communities, and collaboration in education (e.g. supervising PhD-students). Teachers are often involved in co-developing classroom materials and assessments. The Freudenthal Institute also offers the Reken Web, which is available in English as well as Dutch, German, Portuguese and Spanish and provides numerous math games which can be browsed or selected by age group (ages 5 - 12). A significant amount of the institute's publications are available online. Additional publications and resources are available for purchase, some in Dutch and English.