This article presents the contextualised interpretive analysis of communicative practices (artefacts including a song and a comic strip) developed by economically disadvantaged secondary students from two Brazilian public schools. Students' uses of standard and popular languages stretch and problematise social and cultural constructions about what it means to be "literate" currently. The linguistic analysis and the inter-textual analysis of students' multi-modal texts exposed the tensions and the intricacies between rigidly standardised mainstream norms of grammar and socially and culturally embedded textual production and language use at play in many K-12 schools. The analysis challenges current reductionist social conventions about cultural production and language use to further a conception of language that centers difference, change and creativity. It explores the complexity of the artefacts produced by the students according to their hybrid cultural practices, their context and their access to information and communication technologies (ICT). It indicates that students' use of language and multi-modalities presented in the artefacts extrapolates narrow definitions imposed by social conventions about certain language uses (including grammar conventions) and communicative practices. This poses challenges to schools operating according to narrow, ideological conventions that may hurt students' abilities to use language, to communicate and to learn.