Mathématique moderne: A pioneering Belgian textbook series shaping the New Math reform of the 1960s

In 1963 the Belgian mathematician and mathematics educator Georges Papy published the first volume of his groundbreaking textbook series entitled Mathématique moderne (MM) (in collaboration with Frédérique Papy), intended for students from 12 to 18 and based on several years of classroom experimentation. It marked a revolution in the teaching of mathematics and in the art of textbook design. Papy reshaped the content of secondary school mathematics by basing it upon the unifying themes of sets, relations and algebraic structures. Meanwhile, he proposed an innovative pedagogy using multi-colored arrow graphs, playful drawings and 'visual proofs' by means of drawings of film strips. During the 1960s and early 1970s, translations of the volumes of Mathématique moderne appeared in European and non-European languages and were reviewed in mathematics education journals of that time. Papy's MMs influenced the national and international debates and became major guides for shaping the New Math reform in several countries.