In this third volume of Revista Pensadero, we have compiled texts that we believe will be of particular interest to secondary, high school and university teachers, as well as to students of teacher training programmes and Master's programmes in teacher training (however, Pensadero covers all educational levels). Undoubtedly, the volume's Mexican heritage will be of particular interest: three of the five articles on systematized practices have crossed the Atlantic to reach us here... (Excerpt from the presentation: What We Believe in).