Cerebral activity is an intangible physiological process that is difficult to apprehend, especially for children. To overcome this difficulty, Teegi was designed as a new type of educational support. This tangible interface enables children to discover the relationship between brain activity and the functions of the human body. We developed a multi-methods research approach to estimate the pedagogical potential of Teegi used in a real-life educational context. Using this interdisciplinary methodology, we conducted a user study (N=29) that highlighted the strengths of this interface, both in terms of its usability and its impact on learning. Moreover, results revealed possible improvements to further increase pedagogical effectiveness. This type of interface, as well as the evaluation method that we propose, contribute to extending our knowledge concerning the pedagogical use of new interactive tools at school.