In Brazil, undergraduate curricula are required to include at least 10% of their workload in extension activities, fostering not only academic knowledge but also meaningful interactions with society. For students, such projects represent opportunities to develop soft skills, gain professional experience, and better understand the social relevance of their future careers. In the field of Computing, this requirement opens multiple avenues for action, including initiatives to promote data literacy among school students. Extension projects of this nature not only contribute to the education of public school students, who often lack access to this type of knowledge, but also provide undergraduate computing students with the chance to apply their expertise in real contexts. This article reports on a data literacy extension project developed for public high school students in a Brazilian municipality. The project was carried out by undergraduate computing students and involved the planning, implementation, and evaluation of workshops. The experience highlighted the mutual benefits of such initiatives: while high school students were introduced to data-related concepts and practices, undergraduate participants enhanced their communication, teamwork, and project management skills, and deepened their awareness of the social role of computing education.