This special issue of Revista Latinoamericana de Investigación en Matemática Educativa (RELIME) is dedicated entirely to the articles proposed within the framework of the third Symposium Mathematical Work Space (ETM, in French) which is devoted to the study, development and possible applications of the ETM concept in the didactics of mathematics. The mathematical work and its functioning within the school setting are the foundation of the ETM approach, and in this introduction, before presenting the thematic organization of the contributions; we will summarize this theoretical approach. Its goal is to enrich, in a non-normative manner, the didactic study of the mathematical work of the students and teachers