One issue of concern to teachers is the effect of teaching strategies and students' cognitive style on knowledge construction via online discussions in social networks. This study aimed to explore which teaching strategies lead to better learning performance and which cognitive styles affect learning from teaching strategies based on online discussions in a social network setting. Participants in the study engaged in four discussion activities: an abstract writing (AW) discussion, a collaborative problem-solving-based discussion, a project-based discussion, and a peer-assessment discussion, and the participation was used to facilitate comparisons between each group. The following research questions were examined: (a) what are the differences in knowledge construction behavior among students with different cognitive styles in different online discussions according to quantitative content analysis? (b) Are there different patterns of knowledge construction behavior among students with different cognitive styles in different online discussions? We found that students in the Serialist groups showed better performance in terms of the number and the diversity of knowledge construction behaviors. Further, in terms of teaching strategies, AW discussion activities led to more negotiation, coordination, compromise, co-construction, and knowledge construction behaviors, while problem-solving-based discussion activities led to more information acquisition and sharing. We discuss the results and offer suggestions.