ResumenEl proposito de este articulo es investigar procesos de objetivacion relacionados con dos acepciones del numero racional, a partir de la medicion. El enfoque investigativo es cualitativo y considera el estudio de un caso, el cual se focaliza en la interaccion social y en la mediacion instrumental. Las actividades disenadas favorecieron procesos de objetivacion en el seno de practicas sociales orientadas hacia la solucion de una tarea matematica sobre medicion. La mediacion como un punto de partida permitio establecer un vinculo con la produccion cultural historica de los artefactos que usan los ninos no unicamente para producir y reproducir conocimiento sino tambien para apropiarse de significados culturales.AbstractThe objective of this paper is to research objectification processes related to the rational number as a ratio and as a whole number through measuring tasks. e research approach is qualitative and considers a case study which focuses not only on the social interaction but also on the instrumental mediation. e tasks were designed to promote the objectification processes of the rational number as a ratio and as a whole number within the social practice which fosters the mathematics task solution. Mediation as a starting point promoted linking the cultural production of artifacts used by kids not only to produce and reproduce knowledge but also to take over cultural meanings.