Introduction: The theory of registration of semiotic representations establishes that the use of sign systems, which allow the cognitive activities of formation, conversion and treatment, is essential to have access to mathematical objects or processes. Objective: This research aims to analyze the strategies used by eleventh-grade students to solve problems of interpretation and representation through treatment and conversion activities. Methodology: A questionnaire was selected with questions of the type Saber tests, in which the competence of interpretation and representation is evaluated. Also, to show what each student does and says when answering the questions, video recordings and transcriptions are made. Results: An a priori analysis is proposed per question, to analyze and interpret the cognitive treatment and conversion activities used by thestudents, as well as an a posteriori analysis where the results obtained are analyzed and the hypotheses are verified. Conclusions: It shows how students associate the significant units of a problem posed in a representation register to another register, to find either a contrast of the information or a relationship in the information, , taking into account the semantic correspondence and semantic univocity.