Transformation of the Specialized Knowledge of Future Primary Teachers on Fraction Division

Background: an important field of research in mathematics education is the initial training teachers where deficiencies disciplinary and didactic knowledge required for their profession can be evidenced. Objective: To study transformation specialized future about division fractions. Design: qualitative descriptive paradigm a case approached. Context participants: group three students who design, reformulate implement mathematical tasks during Lesson Study environment using Didactic Analysis method, they receive feedback from peers trainer. Data collection analysis: data obtained written productions record recordings class discussions, which were analyzed content analysis method categories model. math teacher. Results: show change knowledge, starting process with design problem situation different meaning conceptual fractions, becomes multiplicative structure type "isomorphism measure". Conclusions: deepening processes first formative stage give us insights on how to improve aiming at professional teaching development.