Collaborative concept mapping, as one of the widely used computer-supported collaborative learning (CSCL) modes, has been used to foster students' meaning making, problem solving, and knowledge construction. Previous empirical research has used varied instructional scaffoldings and has reported different effects of those scaffoldings on collaboration. To further examine the effects of instructional scaffoldings, this research implements three different instructor participatory roles (i.e., "cognitive contributor," "group regulator," and "social supporter") to support online collaborative concept mapping (CCM). We use multiple learning analytics methods to examine the group's CCM processes from the social, cognitive, and metacognitive dimensions, supplemented with assessments of the concept maps. The research reveals different effects of three instructor participatory roles on the group's collaborative behaviors, discourses, and performances. When the instructor engaged as a "cognitive contributor," the student group achieved a lowly-interactive, low-level metacognitive engagement and behavior-oriented knowledge construction; when the instructor engaged as a "group regulator," the student group achieved a socially-balanced, high-level metacognitive engagement and behavior-communication-interrelated knowledge construction; and when the instructor engaged as a "social supporter," the student group achieved a highly-interactive, medium-level metacognitive engagement and communication-oriented knowledge construction. Based on the results, this research proposed pedagogical, analytical, and theoretical implications for future empirical research of CSCL.