Los profesores y los decimales: Conocimientos y creencias acerca de un contenido de saber cuasi invisible

this article analyzes the knowledge and beliefs a group of 25 elementary school teachers has about decimal numbers and their link with mexican reforms in mathematics at the end of the 20th century. the analysis is based on data collected from questionnaires, interviews, and opinions expressed in a workshop for fifth and sixth grade teachers, with the former in preponderance. the results show that, despite the mathematical and functional importance decimals have, these numbers constitute a quasi-invisible content in primary education, because the teachers' main concerns and actions center on how to write using "the point" minimizing and even excluding attention to the conceptual aspects of these numbers. it also offers decisive evidence that their knowledge of the math and teaching technique of decimals is quite limited, which sheds light on the approaches observed and the likelihood that the curricular innovation they are involved in will be overlooked unless institutional conditions are overhauled.