Professores são convidados a introduzir uma aula expositiva numa sequência didática planejada. Os professores tiveram bastante dificuldade para localizar a atividade dentro do que concebiam sobre ensino e aprendizagem significativa. Diante da tarefa proposta, procuraram sistematizar os conteúdos anteriormente desenvolvidos na sala de aula, atribuindo novo sentido à estratégia, sem abandonar a importância de ouvir o aluno e de articular adequadamente os conceitos. A aula expositiva de cada um foi ressignificada, aparecendo com posição definida na sequência pedagógica e com conteúdo significativo em relação ao nível de conhecimento do aprendiz. A conclusão fundamental foi que, mesmo sem ser explícito, era possível haver diálogo entre os saberes do professor e dos alunos, o que parece ter ocorrido também com os professores enquanto aprendizes no programa de formação.<br>Teachers from a professional development program were invited to introduce expository classes (lectures) inside a pedagogical sequence they had planned. Classes were analyzed with criteria seeking to situate them within constructivist conceptions of teaching practice. The teachers had considerable difficulties in locating the activity into what they understood as teaching and meaningful learning. Facing the task proposed, they sought to make a systematization of contexts previously developed in the classroom, attributing new meaning to the strategy without abandoning the importance of listening to the learner and adequately articulating concepts. The expository class was given a new meaning, appearing with a defined position in a pedagogical sequence and a meaningful content in relation to the apprentice's level of knowledge. The most fundamental conclusion was that, even if not explicitly, it is possible to have dialogue between the teacher's and students' knowledge. This seems to have also occurred with the teachers themselves while learners in the teacher education program.