This report presents the results of a research that inquired about the effects over freshmen of initial Mathematics courses at university have on the learning of contents which aims to the comprehension and use of deductive structures frequently used in reasoning or argumentations. This issue is interesting in Uruguay, because of students' high rates of desertion at first year. Antecedents to this study are an analysis of textbooks and classroom notes taken by students, in search of evidence about how explicit are these structures in teaching practices. Among the results observed, it may be highlighted that only the participation in Mathematics courses, in absence of intentional instruction, seems not to be enough to acquire skills on these subjects, and only few evidences were found that shows that teaching takes in consideration instruction in Logic, except in specific texts or courses.