In consideration of the potential of drawing and writing as assessment and learning tools, we explored how early primary students used these modes to communicate their science understandings. The context for this study was a curricular unit that incorporated multiple modes of representation in both the presentation of information and production of student understanding with a focus on the structure and function of carnivorous plants (CPs). Two science teacher educators and two first-grade teachers in the United States co-planned and co-taught a multimodal science unit on CP structure and function that included multiple representations of Venus flytraps (VFTs): physical specimens, photographs, videos, text, and discussions. Pre- and post-assessment student drawings and writings were statistically compared to note significant changes, and pre- and post-assessment writings were qualitatively analysed to note themes in student ideas. Results indicate that students increased their knowledge of VFT structure and function and synthesised information from multiple modes. While students included more structures of the VFT in their drawings, they were better able to describe the functions of structures in their writings. These results suggest the benefits for student learning and assessment of having early primary students represent their science understandings in multiple modes.