ln the educational environment, the qualitative methods of research are seen as anoption in the classroom for unveiling the teachers’ conceptions when they are the“actors” in the teaching learning of sciences process. The results shown were collectedusing a study case methodology. The purpose is not to criticize the two scienceteacher’s rol, nor even their docent action, en the contrary, this is a reflection about thedifferent knowledges, methods and techniques employed by the teachers in theclassroom.