Tabla de Contenidos: “…– A summary, Petra Scherer, Kim Beswick, Lucie DeBlois, Lulu Healy, Elisabeth Moser Opitz -- Mathematics teachers working and learning through collaboration, Barbara Jaworski, Olive Chapman, Alison Clark-Wilson, Annalisa Cusi, Cristina Esteley, Merrilyn Goos, Masami Isoda, Marie Joubert, Ornella Robutti -- Geometry education, including the use of new technologies: a survey of recent research, Nathalie Sinclair, Maria Bartolini Bussi, Michael de Villiers, Keith Jones, Ulrich Kortenkamp, Allen Leung, Kay Owens -- Part 4: Reports from the Thematic afternoon -- European Didactic Traditions in Mathematics – Aspects and Examples from four Selected Cases, Werner Blum, Michèle Artigue, Maria Alessandra Mariotti, Rudolf Sträßer, Marja Van den Heuvel-Panhuizen -- German-speaking traditions in mathematics education research, Hans Niels Jahnke, Rolf Biehler, Angelika Bikner-Ahsbahs, Uwe Gellert, Gilbert Greefrath, Lisa Hefendehl-Hebeker, Götz Krummheuer, Timo Leuders, Marcus Nührenbörger, Andreas Obersteiner, Kristina Reiss, Bettina Rösken-Winter, Andreas Schulz, Andreas Vohns, Rudolf vom Hofe, Katrin Vorhölter -- What is and what might be the legacy of Felix Klein? …”