In this paper, a teaching experience carried out within the framework of the subject of mathematics is presented. This subject is taught at several levels in secondary schools. In addition to some specific content related with mathematics (percentages, fractions, graphics, and bank interest), the methodology is designed in order to enhance the development of transversal skills (e.g., oral exposition, poster design and presentation, the analysis of social inequalities, etc.). Survey results based on the responses from over 110 students across four consecutive years, as well as the teacher's self-assessment, indicate that the proposed methodology enhanced the students' motivation and was helpful for developing mathematical content in a more pleasant way than in a conventional class based on a master class and problem-solving class.