This study contributes to our understanding of meaning making in CSCL environments by examining a specific aspect of collaborative problem solving in which students improvise, introduce, and make meaning with representations in disciplinary domains. These situations include the embodied and imaginative processes of discovering new representational possibilities and artifact meanings. Much of the research on student-generated representations examines situations in which students are asked by a teacher or researcher explicitly to produce representations. However, we need more knowledge about how students within CSCL settings introduce representations from outside of the designed environment or intended task in order to solve a problem. To unpack the processes of collaborative improvisation and meaning making, we take a sociocultural stance towards imagining. This stance involves considering the socially and materially situated ways that participants express new possibilities and alternative situations that extend beyond the present reality. Focusing on a specific task based on maps as disciplinary representations, we analyze video data of upper secondary physics students working in small groups in a co-located CSCL environment. To characterize shifts across boundaries of several modalities including the verbal and gestural, digital and physical, and 2-dimensional and 3-dimensional, we identify emergent representations as imaginative productions. The findings extend current research on collaborative meaning making by bringing attention to the processes through which improvised representations emerge. This knowledge is key to facilitating the discovery of representational possibilities in CSCL environments.