The case of Lucina must be placed at a level of a partial advance achieved in the development of an exhaustive qualitative research recently conclude in a night elementary school of Mexico City, an institution that provides young people and adults with academic formation. The research problem herein discussed is the enrichment of semantic and conceptual contents of fractions in relation to the solution of arithmetic problems that allow the reconstruction of previous vital experiences of the subjects. The case of Lucina is analyzed in light of the application of an exploring questionnaire that preceded to realization of two didactical interview applied to a 41-year-old woman attending to sixth grade of elementary school. The didactical interviews were the main source of information in the study reported herein. (Contains 6 figures.) [For complete proceedings, see ED489597.]