We analyze the interaction of 3 students working on mathematics problems over several days in a virtual math team. Our analysis traces out how successful collaboration in a later session is contingent upon the work of prior sessions and shows how the development of representational practices is an important aspect of these participants' problem solving. We trace the formation, transformation, and refinement of 2 problem-solving practices (i.e., problem decomposition and inscribe first solve second) and 2 representational practices (i.e., modulate perspective and visualize decomposition). The analysis shows how inscriptions become representations for the group through a historical trajectory of negotiation: Learners appropriate inscriptional resources over time as they develop their representational competencies. We show how analysis of the contingently relevant situation may reach into temporally prior episodes in which interaction relevant resources and practices are constructed. (Contains 4 tables and 9 figures.)