Unified Modelling Language (UML) class diagrams are standard tools in software engineering education, typically analysed for syntactical correctness rather than their communicative dimensions. This study applies semiotic theory to investigate how first-year Bachelor of Computer Information Systems students engage with UML class diagrams as communicative artifacts. Using a narrative research approach based on the integrated-methods research framework, data was collected through individual semi-structured interviews incorporating think-aloud protocols with 11 participants. Participants completed tasks of increasing complexity: analysing simple diagrams, describing relationships between classes, and creating their own class diagrams. Data analysis followed a systematic coding framework aligned with the six semiotic principles: identifying diagram elements, deciphering signs and symbols, understanding the contextual significance, interpretation and meaning, contextualisation within broader discourse, and critical reflection. Findings reveal that students employ diverse strategies when approaching UML class diagrams, with consistent analytical approaches yielding better comprehension. Visual elements significantly influence interpretation, while terminological confusion and cognitive load present key challenges. This research contributes to UML pedagogy by highlighting the need for educational approaches that address both technical notation and interpretive strategies, balancing concrete examples with abstract structural thinking.