We present our work within the project, aimed at preventing school drop-out in disadvantaged suburbs of Naples. Specifically, we present aspects related to the educational design and teacher training, discussing methodological choices and providing examples of activities oriented to citizenship education's objectives and to the development of positive attitudes towards mathematics, and more generally towards school. Starting from the experience in the project, we present our reflections on the construction of informal mathematics education contexts, developed to also include students who experience serious socio-cultural disadvantage, and on the related teacher course. We believe that the latter is essential for the development ofeffective didactic approaches to mathematics, which take into account democratic ideals, and that are located in the history, culture and specific needs of a specific territory.