Recent studies in learning programming have largely focused on high school and college students; less is known about how young children learn to program. From video data of 20 students using a graphical programming interface, we identified ideas that were shared and evolved through an elementary school classroom. In mapping these ideas and their resulting changes in programs and outputs, we were able to identify the contextual features which contributed to how ideas moved through the classroom as students learned. We suggest this process of idea mapping in visual programming environments as a viable method for understanding collaborative, constructivist learning as well as a context under which experiences can be developed to improve student learning.