Critical thinking (CT) is a goal pursued by the field of science education in the 21st century. However, CT often appears as a cometic criticism or something without a deeper understanding of the issues analyzed. In this paper, we mobilize references capable of giving visibility to CT components under development in science lessons interactions. Based on Ethnography in Education, we followed science lessons of a class over 8th and 9th grades of Elementary School and selected discursive interactions for CT analysis, during the debate on a controversial issue. Instructional contexts experienced by the classroom became resources for students to position themselves, understanding the relevance of using and evaluating scientific evidence and evidence from other domains, in addition to the collaborative role in the construction of democratic positions. These results align with paths that have been thought of by the Science Education field for a post-truth era.
