How can we make use of image-based social media to develop students' critical engagement with concepts like equality and diversity? In this paper, I draw on bell hooks' description of liberatory theorising to discuss findings from a project that involved 60 2nd year BA education students taking and sharing photographs through Instagram as part of their learning on a sociology module underpinned by a critical pedagogy approach. Thematic analysis applied to ten interviews with student participants shows that while the project supported students to connect everyday experiences with abstract concepts, their criticality was hindered by the perception of the task as one of 'capturing' unambiguous representations of concepts. The findings highlight that if we are to use popular image-based social media sites as part of a critical pedagogy approach, we need to be prepared to support students in using the visual mode as part of liberatory theorising.