This study investigates the process of collaborative knowledge construction when technology and pictorial knowledge representations are used for visualizing individual and groups' shared ideas. The focus of the study is on how teacher-students contribute to the group's collaborative knowledge construction and use each other's ideas and tools as an affordance for their jointly evolving cognitive systems. The context of the study is a teacher-student (N=13) educational technology course. The data involved students' videotaped face-to-face group activities (mindmapping with paper and pen and mind-mapping with a Mobile Mind Map Tool and pictorial knowledge representations) as well as stimulated recall interviews. The data-driven qualitative content analysis revealed that students were engaged in knowledge level and transactivity level activities and they processed their own ideas as well as others' ideas in their group interactions. (Contains 6 tables and 1 figure.)