In the context of scholarly and scientific discourse, students often have to deal with graphic-visual modes of communication, which requires their ability to comprehend and utilize inscriptions, that is, scientific visual representations, to convey information effectively--what we call graphical literacy. Despite its pivotal role for training scientists and facilitating scientific communication, there is a lack of resources for assessing the graphical literacy of undergraduate students during oral presentations (OPs), a common assignment in post-secondary educational contexts. This study addresses this gap by investigating the graphical literacy of first-year chemistry undergraduate students by analyzing the inscriptions they used during multimodal OPs designed to display the resolution of a problem posed through interrupted case studies. Our results are presented as claims that highlight how students' engagement with inscriptions in OPs makes evident their graphical literacy. These findings have significant implications for educators, providing guidance for assessing graphical literacy and the effective use of inscriptions in OPs.