The research aims to investigate the educational practice of science teachers who work in prison education. We assume that, in the absence of professional and academic formation in the field, these teachers end up using in their jail classes the same didactic strategies carried out in schools outside the prison, underestimating the specificities of prison education. In this sense, the aim is to characterize the teaching practices developed in prisons, recognizing the specificities of science teaching in this school modality. The sample consisted of 10 teachers who taught/teach the scholar discipline Sciences - final years of Elementary School - in prison schools established in closed prison units (maximum security), male gender, located in the Penitentiary Complex of Gericinó, in the municipality of Rio de Janeiro. The data, obtained through a semi - structured individual interview, were treated qualitatively based on the Content Analysis - Thematic Analysis modality. The categories of analysis were constructed, mainly, from the theoretical reference of Tardif (2002) on the nature of the teaching knowledge. The interpretation of the collected information points to the importance of the teaching knowledge coming from the professional experience in the jail. That is, it is in the everyday classroom that the science teachers construct their practices.