The aim of this paper is to reflect on the ability of high school students to collect and interpret data on their indoor environment when equipped with low costs sensor devices. The paper draws upon practical examples from case studies in CITI-SENSE project carried out in three European cities and highlights areas for consideration when engaging high school students in data gathering and interpretation. As a “citizen science” project CITI-SENSE is testing and developing low-costs air quality sensor units for participatory sensing. Collaboration between local research institutes and high schools resulted in various student research assignments. The quality of the data produced by high school students was not only affected by their capabilities to -contribute to scientific research, but also by the limitations of the provided tools. However, we concluded, that as long as students are supervised, they are capable of contributing to scientifically sound research.