This article addresses issues related to traces modelling for formally describing human interactions of people engaged in a synchronous collaborative learning activity. The objective is to propose models and tools for representing, transforming, sharing and visualising traces of users' experiences. The traces here represent the users' activities in their interactions with the learning platform. Our proposition is based on reflexive learning defined as the ability to interact with the situation, in order to meet one's own limitations. This work takes place in the ITHACA project which aims at developing an on-line learning platform that uses interaction traces as knowledge sources on, and for, the learners' learning as individuals or groups. In this paper, we propose a general framework for trace management and sharing, a generic model of synchronous collaborative activity based on the notion of interaction modes that we specialized for whiteboard sharing and text chatting, and a conceptual framework for modelling the exploitation of modelled traces, in particular for interactive visualisation on the user side. This article extends our previous work [1] on the instrumented prototypes, by presenting our theorisation of the interactive visualisation of modelled traces.