Uno de los principales problemas que surgen al trasladar una tarea de modelizaci on matem atica al aulade secundaria es la falta de una descripci on detallada, desde la perspectiva de la did actica, que ayude yoriente al profesor en servicio en la implementaci on de este tipo de actividad y que le permita identi carcu ales son los objetivos de aprendizaje que se persiguen; su encaje dentro del curr culo o cial; el tipo detareas que permiten alcanzar estos objetivos; c omo realizar su evaluaci on o qu e metodolog a utilizar. Eneste art culo abordaremos todos estos aspectos a partir de una experiencia de aula, detallando cada unade las fases implicadas en la implementaci on de una actividad de modelización. One of the main problems that arise when implementing a mathematical modeling task to the secondary classroom is the lack of a detailed description, from the didactic perspective, that helps and guides the in-service teachers in the implementation of this type of activity and that allows them to identify which are the learning objectives being pursued; if this kind of activities fit within the official curriculum; the type of tasks that allow these objectives to be achieved; how to carry out their evaluation or what methodology to use. In this article we will address all these aspects from the perspective of a classroom experience, detailing each of the phases involved in the implementation of a modeling activity.