This article examines how school students perform gender during a visit to a science centre where they programme Lego cars. The focus is on how students relate to each other--how they talk and what they do. Theoretically, the article draws on the 'heterosexual matrix' and a Foucauldian understanding of how power and knowledge are tightly interwoven and that discursive practices regulate people's possible positions and ways of being in different situations and contexts. The analysis is primarily based on video data from the science centre and a number of student interviews. The article gives several examples of how stereotypical gender performances are maintained but also challenged. This is important knowledge, because if we want to challenge norms, we first need to see them and understand how they are reproduced.