Piet Vredenduin: math teacher and more, trait d'union between the Dutch and Flemish mathematics teachers' communities

Piet Vredenduin (1909-1996) played a prominent role in the Dutch mathematics education community during the second half of the twentieth century: mathematics teacher, mathematics researcher which led him to a dissertation on Fraenkel's Mengenlehre applied to number theory, author of mathematics textbooks for almost all sections of the secondary mathematics curriculum, mathematics teachers' educator, participant in two innovating projects: teaching history of mathematics, and statistics and probability theory in secondary education, contributor and editor of the journal of the Dutch association of mathematics teachers. Last but not least, he played an important role in the implementation of the ideas as discussed at "Royaumont" ("New Math"). These are his main activities inside the Netherlands. Internationally we have to mention his role as a trait d'union, "a liaison officer", between the Dutch and the Flemish communities of mathematics teachers: representing the board of the Dutch mathematics teachers association on many occasions in Flanders, contributing articles to the journal of the Flemish mathematics teachers' association, informing the Dutch mathematics teachers about the developments in Flanders, and the Flemish teachers about the developments in the Netherlands, especially about the implementation of the recommendations of "Royaumont".