Literacy today relies on a readers' ability to analyse text critically. This case study investigated preservice teachers' critical analysis of media text containing visuals and representations. In particular, the analysis focused on mathematical factors that impact on readers' interpretation of diverse visuals. Data was gathered from the 23 preservice teachers, enrolled in the Graduate Diploma program at one Australian university. They participated in a series of mathematics learning sessions focused on the critical analysis of a selection of media items. The paper argues that the ability to critically analyse graphs and visuals relies on mathematical knowledge and that the ability to critically analyse such representations is a necessary component of mathematical literacy and everyday literacy. Mathematics teachers require well-developed critical analysis competencies to enable them, and ultimately their students, to critically analyse representations in everyday text. The paper illustrates that drawing on diverse visuals from the media can be productively used to develop critical analysis competencies.