<p>A crucial challenge in developing environmental literacy for sustainability is systems thinking. Grasping the effects of humanity’s disruption of the carbon cycle is necessary for making informed climate decisions. Systems thinking could potentially be supported through interactive visual learning environments. We investigate pupils’ use and assessment of “Tracing Carbon”, an interactive learning environment designed to support grade 7–9 pupils’ systems thinking skills in the context of the carbon cycle. The study aims to fill a gap in exploring relationships between task design and behaviors with such platforms by examining pupils’ task performance and their evaluations of the learning experience. Data were collected from 97 pupils across three classes in grade 8 and 9 that engaged with Tracing Carbon as part of science lessons. Pupils’ performance was analyzed through log files of interactive tasks and additional data gathered from assessment of quiz items. Pupils’ performance across tasks showed higher error rates in more complex tasks such as drawing arrows to represent carbon cycle processes, and more mistakes in tasks with complex connections. Some errors could stem from misunderstandings such as believing trees receive all their nutrition from soil, instead of carbon dioxide in the air. The logs reveal the presence of patterns in pupils’ arrow-drawing actions, possibly indicating different problem-solving strategies. Pupils generally evaluated their learning experience as more instructive than fun or interesting, with female participants finding it significantly less interesting than males. Findings may inform the design of interactive science learning environments and the analysis of pupils’ development of systems thinking using such tools.</p>