Current literature indicates a lack of exploration of factors relating to Taiwanese students’ critical thinking in the field of English as a Foreign Language (EFL). The research study was a case study based on the social constructivist framework. The aim of this study was to explore how teacher and students interactions online impacted critical thinking by addressing the social norm in Confucius Heritage Culture (CHC). The characteristics of the social norm of CHC do not readily support verbalizing thoughts and challenging others face-to-face in public, which are important to the practice of critical thinking. The research was conducted in an English-major reading class at a university in Taiwan. The data collection methods included focus groups, collaborative inquiry with the teacher, and the researcher’s participant observation in both face-to-face and online discussions. The findings suggested that students need teacher’s cognitive, affective, pedagogical and technical support and face-to-face small group support before engaging in online interactions. Modified debates in new face-to-face models of interaction helped maximise the social constructivist approach with the teacher’s shepherd facilitation. The online interaction patterns in a CHC context underwent a three-phase process, which described how CHC students externalised critical thinking within groups, inter-groups and inter-classes in online form. The study contributes to our understanding and the development of culturally suitable approaches to cognitive, affective, pedagogical and technical guidelines needed in facilitating EFL students’ critical thinking in face-to-face and online interactions in the context of Taiwan.