This thesis presents visualisation as a method for research on learner interaction. The visualisation is designed to account for the dynamics of learner interaction across the duration of language classroom activities. The development of this method includes the formulation of a dynamical perspective on learner interaction, which draws on sociocultural and complexity theory. The visualisation is developed with, and applied to, data from three pairs of participants engaged in a series of similar English writing activities in a Norwegian primary classroom. The thesis provides a detailed discussion of how this learner interaction data was transcribed, coded and eventually visualised. The application of the visualisation to the Norwegian primary classroom data resulted in the identification of patterns and phases in the participants' learner interaction. These patterns and phases revealed both common and unique dynamics across the three cases of interaction. The outcome of the visual analysis of one of the cases was used to guide an in-depth analysis of episodes of learner talk. This in-depth analysis confirmed some of the dynamics established by the visual analysis. A final visual analysis identified different change processes in the three cases of learner interaction across the series of similar writing activities. Overall, the visualisation helped to make transparent how both the writing activity and the participants' own contributions affected the dynamics of learner interaction. The thesis concludes that, in the terms of the dynamical perspective developed by the thesis, visualisation was an effective method for describing the dynamics of learner interaction in the writing activities the participants were engaged in. The thesis also suggests that visualisation can be used in conjunction with other methods for researching learner interaction. Finally, the thesis points out some limitations of the present implementation of visualisation, and makes suggestions for how the method can be improved through further research.