Although visual aids are widely considered a valuable source of scaffolding, the nature and active utilization of these aids in current science classrooms are not well understood. This qualitative study explores interaction in the teaching of concepts related to evolution, with a specific focus on a teacher's use of different visual support material. Based on a classroom study in a linguistically diverse Grade 4 classroom, we employed the perspective of discourse-bridging interaction to develop three broad categories of interactional examples, which we related to three kinds of visual support material used in the instruction: generic visual support images, naturalistic images, and disciplinary images showing examples of natural selection. The findings show that the interaction moved in and out of science discourse in a way that reflected the images' properties. A generic visual support image illustrated the concept of "adaption" as puzzle pieces fitting together, which promoted everyday and anthropomorphic examples of animals and people striving to fit in. When the teacher used naturalistic images, the discourse shifted between a range of perspectives, while visual aids and whiteboard drawings showing the classic examples of giraffes evolving (a disciplinary image) were employed to clarify the notion of natural selection. We discuss the study's implications for using visual support material in a planned way that supports disciplinary understanding.