This article reflects on the importance of analysing the written production of students in order to evaluate learning in school environments. An analysis is presented of the written answers that 25 students, aged 10 years old, of 4th level of Elementary School (Cambé - Paraná - Brazil), gave to a mathematical question. The analysis focused on the following areas: i) which steps the students took to solve the problem; ii) what mathematical knowledge they used; iii) what kind of mistakes they made; iv) how the students used the information provided by the question statement. The article highlights the fact that the students used some kind of mathematical knowledge even when their answers were wrong. It emphasizes evaluation as a way of improving our understanding of the teaching/learning process.
Mathematics Education; Mathematics assessment process; Mathematics written production; rightness and errors