This book is a friendly and complete introduction to one of the most comprehensive contemporary theories of mathematics teaching and learning. By focusing on mathematical work performed by students and teachers during mathematics session, the theory of Mathematical Workings Spaces (MWS) has opened up new perspectives and avenues on mathematics education and mathematical thinking. In particular, it enables the identification of students' knowledge production processes and helps teachers to shape them.The first part of the book explores the heart of the theory and aims to further describe and understand epistemological and cognitive aspects of mathematical work. The second part develops the different MWS dedicated to observing how this work d...