The number of women in technical fields is far below the average number of males, especially in developed countries. Gender differences in STEM are already present in secondary schools in students aged between 12 to 15 years. Adolescence is a critical time for identity formation, and self-attributes are a source for internal conflicts, especially for female teenagers. It is during this intermediate female adolescence that girls begin to make critical career choices, which therefore makes this a key age to reinforce them and reduce the gender disparities in ICT. Computational thinking skills are important from a philosophical point of view, since they allow us to understand the foundations of rational thought in a clear, easily understandable, but also inspiring and challenging way. To address the gender bias in schools, one of the goals of the European H2020 project No One Left Behind (NOLB) included integrating Pocket Code, a free open source app developed by the non-profit project Catrobat, into different school lessons. Through game design, Pocket Code allows teenage girls to incorporate diversity and inclusiveness, as well as the ability to reflect their cultural identity, their emotions, their likes, and their ways of interacting and thinking. To evaluate the impact of the use of the app in these courses, we captured the results on engaging girls in design and coding activities. For this paper, the authors present the data of surveys during the second cycle of the project. With a focus on female teenagers, the results allow us to conclude that a suitable classroom setting is significantly more important for them than the coding tool itself.