The Masterclass of particle physics is an international outreach activity which provides an opportunity for high-school students to discover particle physics. The National Institute of Nuclear Physics (INFN) in Pisa has taken part in this effort since its first year, in 2005. The Masterclass has become a point of reference for the high schools of the Tuscan area around Pisa. Each year more than a hundred students come to our research center for a day. They listen to lectures, perform measurements on real data and finally they join the participants from the other institutes in a video conference, to discuss their results. At the end of the day a questionnaire is given to the students to assess if the Masterclass met a positive response. Together with specific questions about the various activities they took part in during the day, we ask them if they would like to become a scientist. They are offered about ten possible motivations for a ‘yes’ or a ‘no’ to choose from. The data collected during the years have been analysed from a gender perspective. Attracting female students to science and technology-related careers is a very real issue in the European countries. With this study we tried to investigate if male and female students have a different perception of scientific careers. At the end, we would like to be able to provide hints on how to intervene to correct the path that seems to naturally bring male students towards STEM disciplines (science, technology, engineering, and math) and reject female students from them.