This research to practice full paper explores the role of programming workshops for girls of primary education in changing perceptions and interests of this audience regarding joining this field. A programming workshop with the playful environment Scratch and a teaching-learning approach based on challenges was held in a middle school of city in the northeast of Brazil, and was analyzed using a mixed-methods case study. Results point to increased interest in the field after the workshop and no confirmation of erroneous stereotypes about the area. We conclude that this type of workshop is relevant to better understand and potentially improve girls' perceptions about the field of computing.