Research on labour market disparities between men and women has long since identified horizontal segregation in the educational system as one of the main factors driving the gender pay gap. One of the factors identified in the literature believed to be at the heart of horizontal gender segregation is the lack of representation and visibility of women in STEM fields. In this paper, we investigate the effectiveness of a program named “STEM in Genere”, developed within the Gender Equality Plan 2022-2024 of the University of Brescia (Italy), which is aimed at contrasting the underrepresentation and the stereotypical representation of women in science among primary and lower secondary school students. Students of participant classes will meet an educator for a total of 2 hours, in which counter-stereotypical thinking of women in science will be stimulated via learning games. Teachers of participant classes will follow in parallel a dedicated workshop about non-stereotypical science teaching. The effects of the program on students' gender stereotypes in science and study/job aspirations will be evaluated via a randomised controlled trial (RCT) conducted in primary and secondary schools of the Brescia province, an affluent province located in the northern part of Italy. In particular, we will randomise classes within participating schools to have a good balance between the statistical power of the experiment and potential contamination threats. The contribution of this evaluation is threefold. First, we will collect first-hand data on students' views and aspirations in a country - Italy - in which the population traditionally holds quite conservative views about gender roles. Second, we will provide robust, experimental evidence on the effectiveness of the program “STEM in Genere”, which is potentially scalable nationwide. Lastly, we will contribute to the methodological debate about question framing in survey methodology, by randomly varying the formulation of the questions in the surveys. Policy implications for educational and learning environments will be discussed.