This paper concerns with the use of digital storytelling in mathematics education as a competence-based methodology. It seems to be well apt to improve students' capabilities be active solvers of real world problems, according to PISA framework. We present a storytelling model, which takes into account both research results about storytelling from pedagogical area and from story problems in mathematics education. According to the model, we present a use case, consisting in the implementation of a prototype. This latter has been made available to the Regional School Office of Campania (South of Italy) in the context of a project to support schools activities regarding mathematical literacy. Finally, we report some early students' perceptions and discuss the constraints and limits of the prototype.