We report on a design based research study exploring how the organization of classroom activity impacts early elementary students' critical criteria for evaluating representations in science class. The ability to critique representations produced by others as well as one's own is an important practice when working with representations. Effective critique requires understanding the purpose of the representation and the context of its use. We use Activity Theory to explore how a change in teacher prompts can facilitate a shift in how the teacher and the students organize their collective activity ultimately resulting in a change to the nature of their critical criteria for evaluating their peers' representations. To explore this relationship, we worked with a teacher to iteratively adapt and refine whole-group discussions of students' representations to provide a context in which students critique their peers' work on scientific grounds. After each representational activity, the teacher engaged the students in discussing the representations (three groups of students across a total of six sessions, N = 39). Findings indicate that contextual cues lead to a statistically significant shift in students talk. Video analysis indicates that shifts in contextual cues resulted in dramatic shifts in how the activity is mediated, resulting in the verbalization and application of increasingly robust scientific criteria across three different sessions.