Geological time is by many geoscience instructors considered a threshold concept for geoscience students, being a central concept for how we experience geosceince phenomena that takes place on a spatio-temporal scale ranging from micro (e.g. cloud formation) to macro (e.g. plate tectonics). If one wishes to understand geoscience phenomena that goes beyond human perception, one must move from the concrete toward the abstract—from experiencing a phenomenon with one’s senses toward an experience of the phenomenon that is based on an mind construct; we refer to such competency as disciplinary spatio-temporal competency (DSTC). The purpose of this study is to gain an understanding of how first-year students in a geoscience program in Sweden experience and represent the phenomenon of geological time, i.e. to capture their DSTC. Analyazing data from three semi-structured group interviews using a phenomenographic approach revealed how the students express geological time through their language, their gestures, and their visualizations. From the result in this study, including four qualitatively different themes, or categories of description, it is possible to conclude that the students' way of expressing geological time give rise to exciting interpretations and we believe that these expressions can provide information also about how students experience (and learn about) geological time. We report that through students’ illustrations and discussions, students experience geological time as something more than a static one-dimensional straight line. The data analysis shows that students connect geological time with spatio-temporal aspects from various geosientific phenomena, one example of such an dynamic description of geological time is “One simply fills it with more information” indicating that the students experience geological time as two-dimensional (space and time).

To move between different semiotic systems, such as graphs and formulas, is a necessary step in learning physics or solving problems. In social semiotics, this movement of semiotic material is called a transduction and during a transduction a student must unpack, filter, and highlight different aspects of the concept or problem. Unpacking, filtering, and highlighting have been shown to be important to the meaning-making process and transductions should be seen as indicators of meaning-making and learning. However, in this paper we argue that not all transductions performed by students requires unpacking, filtering, or highlighting, and hence the definition of transduction needs to be refined in its description. We introduce the ideas of passive and active transductions that separates transductions that may lead to meaning-making from transductions that may not. This separation is done through shown engagement with the semiotic material of the transduction. We connect shown engagement with the semiotic material to the already established anatomy of disciplinary discernment to create a useful tool when evaluating student engagement and discernment. In the paper, we showcase examples of passive and active transductions and provide a short description of how to identify them in different learning situations.