This case study consists of a classroom ethnography in which the daily basis of physics as a discipline in a classroom of students of the second year of high school, in a Brazilian military school, is described. It comprises a set of more comprehensive ethnographic studies in different types of schools as well as in the context of higher education teaching. It aims at investigating possible contributions of aspects related to the nature of science as a potentially useful strategy for the improvement of physics teaching. The observed physics teacher did not have in his schooling any formal study of epistemological disciplines, so that it was also the goal of this research the identification of his epistemological conceptions and of any feasible relationships between these conceptions and his teaching praxis. Research findings suggested a classroom reality and a school context that seemed to favor cross-examining the existence behaviorist legacy, although under a different disguise, as well as the need to reflect upon the extent to which this legacy can be considered harmful.