The paper presents a pedagogical intervention targeted at secondary school students developed by two researchers in physics. The project seeks to address the gender gap in STEM fields by fostering students’ critical awareness on gender stereotypes and roles, helping them to recognize the influence that gender has on their educational choices and professional aspirations. Unlike other orientation programs, here STEM subjects are not the explicit content, rather the working methodology. Our intervention adopts a project-based learning approach introduced by a board game designed to engage students in the topic. Students are guided in carrying out an autonomous investigation of gender discrepancies within their family, school, and peer contexts through a scientific approach, by administering surveys, gathering and analyzing data, and using gender indicators. The final objective is developing a Gender Report of the school. After presenting the project, we report a qualitative analysis of students’ Reports focusing on the gender dynamics they have identified. Our analysis shows that traditional gender roles and stereotypes persist, yet first-hand observation may stimulate students’ critical thinking skills from a gender perspective.