<p>The development of mathematical skills allows students to get along themselves in different contexts, such as: school, family and social context; communication and modeling are among the fundamental mathematical skills, which have been presenting deficiencies in the fifth grade students of the Technical Educational Institution José Ignacio de Márquez, Antonio Ricaurte building in Ramiriquí; these deficiencies were evidenced in the diagnosis carried out from the analysis of the results of the "saber" tests (<em>name from the Spanish</em>). Therefore, to overcome such shortcomings, it was proposed to work a didactic unit through the resolution of problem solving in order to contribute to the development of communication skills and modeling in mathematics. Methodologically, the study was based on action research, under a critical social approach, framed in the qualitative paradigm. For the development of the study, the methodological design was established in three phases: diagnosis, design of the didactic unit, and analysis of the benefits of the implementation. Afterwards, triangulation, analysis and discussion of the results were carried out; evidencing that working on problem solving situations strengthens the development of communication and modeling competences in a significant way.</p>