The research we present is part of an exploratory study of the pedagogical practices involved in the process of teaching multiplication as carried out by primary school teachers at schools in the Puerto Montt commune, Chile. Given that teachers are agents of change in education, an understanding of their pedagogical practices is necessary in order to contribute to their on-going training, as well as the initial training of mathematics teachers. This study presents the design and construction of an instrument that makes possible to identify the pedagogical practices applied by active teachers when teaching multiplication. The design of the instrument is based on the literature review of the multiplication and its teaching organised in four dimensions: (1) Conception of the didactics of mathematics, (2) Methodology for teaching multiplication, (3) Difficulties in the multiplication learning process and (4) Teachers’ perceptions about mathematics teaching. The validation of the instrument was carried out by peer review, which enabled its adjustment to meet the goals of the study, which are: (1) Identify the pedagogical strategies for teaching and learning multiplication that allow facing classroom diversity, (2) Describe Third Grade teachers’ conceptions about multiplication, and 3) Characterise pedagogical practices carried out by elementary school teachers in multiplication teaching. The application of the instrument has demonstrated its potential for research and educational intervention