In order to investigate the impact of science drawing instruction in a first-grade unit on carnivorous plants (CPs), we analysed student-produced drawings after explicit instruction in drawing scientifically (n=38), as well as compared their drawings with students in a previous implementation (year 1) who did not experience explicit drawing instruction (n=31). The year 2 students experienced a science unit using multiple modes of representation (MMR) that began with a class session focused on the scientific purposes of observational drawings, including the use of labels as a science convention of communication in visual representations. Students who participated in the unit with explicit drawing instruction increased the number of structures and labels that they included when comparing their pre- and post-unit drawings, and included a statistically significant higher number of elements and labels than their year 1 peers. The results indicate that the explicit drawing instruction served as a "semiotic tool" for students as they constructed meaning about the structure and function of CPs, as well as supported early primary students in engaging in the "epistemic practice" of drawing for science communication. Implications of the study include the importance of incorporating explicit drawing instruction into science units involving student-generated drawing.