The aim of this paper is to investigate whether and how three modes of thinking and semiotic perspectives are compatible for researching the teaching and learning of elementary geometry in a dynamic geometry environment (DGE). It first provides an epistemological analysis of compositions of reflections in a line from geometric, analytic and abstract aspects. Then, it represents a design of a task considering semiotic potential of particular tools in the DGE that was field-tested with a pair of prospective primary school teachers. Further, it discusses how has the double analyses allowed a detailed understanding of the semiotic potential of the designed artefact for the development of all three modes of thinking of the chosen geometric concept by the teachers. It finalizes with suggestions for future investigations of development of knowledge of other concepts in geometry through the modes and their support by digital tools.