In the last two decades, one can see the widespread acceptance of the importance of teaching critical thinking (CT) as a 21st-century competency for all students from primary to graduate school. Lack of effective instructional strategies cause problems in developing effective CT curriculum. This research study aimed at the exploring the problem of "domain-general versus domain-specific" tension associated with the definition and fostering critical thinking. We examined Iranian science teachers' conception(s) of this tension. We applied stratified random sampling for the observational phase (initial pool of participants). Using our classroom observation scale, through the lens of the Critical Thinking Consortium's pedagogical framework (TC[superscript 2]) as a theoretical framework, we observed N = 27 gifted science classrooms to evaluate teachers' instructional strategies in terms of developing CT abilities. Applying purposeful sampling, we interviewed expert teachers based on the observational phase, to investigate their understandings of CT's general-domain habits of mind. Applying 4 + 1 classical elements as a conceptual framework, we examined various dimensions of these science teachers' conceptualization of thinking critically. Traditional gradual reduction of interviews resulted in the development of a culturally informed five-elemental pentagram of habits of mind shared by these educators. Further, these teachers addressed some instructional strategies to embed CT in the science classes.