Teamwork, collaboration, and co-construction are terms that have long been addressed. Educators are interested in communication between learners in groups. Their communicative skills and their interpersonal relationships are considered. Interactions in learning are at the heart of the sociocultural theory. This article provides conceptual and empirical information related to online interactions in forums. It aims at exploring students’ knowledge co-construction through forums. A mixed method was adopted to gain deep insight regarding online exchanges. Quantitative data were collected via a survey shared with IFTEC master program students to know their perceptions regarding the use of forums and their importance in the co-construction of knowledge. Qualitative data were collected based on a conversational analysis model and a textual analysis method through “Tropes” software, to release various levels of meaning and number of occurrences. Quantitative data have shown that most participants believe that online interactions are important for the co-construction of knowledge in blended learning. Some measures were suggested to improve the online learning experience. The qualitative data showed that the general style of the content is rather argumentative. The narrator is mostly present with favorable intervention by the tutor. An average level of interactions and a reduced participation rate are noticed. The co-construction is manifested in the dyadic and triadic relationships created in some forums.