This work presents a literature review on active teaching methodologies, particularly Project-Based Learning (PBL), and proposes a learning situation that employs this methodology.The proposed learning situation covers the curriculum portion dedicated to radioactivity and nuclear physics in the Physics subject of the last year of highschool.The literature review conducted shows that PBL is an effective methodology for enhancing student learning and motivation.Furthermore, the importance of the teacher's role as a guide and facilitator in the learning process is emphasized.The learning situation proposed in this article consists of a project on environmental radioactivity, where students are required to investigate the environmental effects and human health impacts of radioactive emissions.The project is divided into several phases, from the initial research to the final presentation of the project to their peers.