This study explores Grade 4 school children's experiences of cross-sex relationships in a co-educational farm school in uMgungundlovu district in South Africa. The aim is to understand if and how constructions of gender bear on young children's social relations at the school. Informed by children's geographies and new sociology of childhood studies, this study uses data from semi-structured interviews and photo-voice imagery based on a qualitative narrative study of three girls and three boys aged between 9 and 12 years. The study found that children's experiences of cross-sex relationships were deeply entrenched in traditional discourses of masculinities and femininities. These rigidly constructed discourses of gender were found to constrain possibilities and fluidities with which children navigated places and spaces of cross-sex relationships in the school. The hegemonic regulatory power of gender norms was a yardstick, informing children's organisation and performances of cross-sex relationships even if some children had developed creative ways of subverting dominant gender norms in how they navigated in cross-sex relationships. The study argues for the liberalisation of gender norms, in order to allow children to freely -- without being constrained by their genitalia -- take subject positions of gender in cross-sex relationships. This would promote sustainable equitable gender relations, as children learn how to engage in cross-sex relationships, beyond the constraining prescripts of dominant masculinities and femininities.