This article is the result of a research project that aimed to characterize the communication skills developed by students who solved problems of seven workshops related to the notions of variation and change within the framework of a pre-calculus laboratory course mediated by interactive mathematical software at a Colombian public university. Data analysis was performed considering the characterization of the skills of interpretation, explanation, and justification, which are fundamental for the communication process of variational thinking. Here we show evidence of the identification of communicative skills manifested by students when solving problems involving the use of the notions of variation, tendency, and approximation.