This contribution analyses the arguments of students in a learning activity entitled "Argue Graph". This activity is intended to make students understand the relationship between learning theories and design choices in courseware development. The analysis of arguments is centered on the effects of discussion and opinion conflict on the elaboration of arguments. We then use an adaptation of a collective intelligence model to describe the knowledge flow among people and artifacts during the learning activity. Finally, the representations produced by the system, used by students to write a synthesis and by the teacher to debrief the class are analysed in relation to metacognition. We propose to consider these representations as metacognitive tools which structure the learning activity.