Promoting progressive discourse and sustained inquiry is a focus area of knowledge building research. Although different approaches for scaffolding productive discourse have been documented, the experimental investigation into the impact of teacher scaffolding on students' knowledge building processes and outcomes in technology-supported environments is limited. Therefore, we designed a quasi-experimental study to examine the impact of teacher scaffolding on students' interaction patterns, social-epistemic networks, and academic performance. Over a 14-week course, data were collected from undergraduates' online interactions, discourse in the Knowledge Forum, and their group artifacts. We employed lag sequence analysis, social epistemic network signature, and the Kruskal-Wallis test to analyze the data and compare the differences between the control and experimental groups. Findings demonstrate that teacher scaffolding can effectively enhance students' reflective behaviors, foster social and epistemic engagement, and improve academic performance within technology-supported knowledge building environments. This study provides valuable insights into the design and implementation of teacher scaffolding to facilitate student knowledge building processes and outcomes.