Cognitive Strategies in UML Class Diagram Interpretation: A Study of Load, Order, and Symbolic Confusion

Unified Modelling Language (UML) class diagrams are critical in computing education, yet students face significant cognitive challenges in interpreting these complex visual-technical representations. Building on prior semiotic analyses of UML class diagram cognition, this narrative study (based on the integrated methodology) applies the Cognitive Load Theory (CLT) to explore how 11 first-year computing students at a South African university manage mental load during the interpretation of UML class diagrams. Through the semi-structured interviews, student-created artefacts, and systematic behavioural observations across three activities of increasing complexity ( simple element identification, relationship analysis, and complex diagram construction ), we identified four primary cognitive strategies: analytical sequencing and prior knowledge; symbolic confusion and clarification; diagram orientation and redrawing; and cognitive load management through decomposition. Participants demonstrated metacognitive awareness of working memory limits, employing adaptive strategies like spatial rearrangement, symbolic error correction, and systematic breakdown of visual complexity. Two key sources of extraneous load emerged: symbolic confusion from ambiguous notation and spatial disorientation from unconventional layouts, prompting compensatory behaviours such as diagram redrawing and self-correction. This exploratory study provides preliminary evidence for the potential application of CLT to visual-technical learning, suggesting that these participants acted as active cognitive agents. Pedagogical implications include explicit training in systematic analysis, symbol fluency, standardised visual designs, and metacognitive strategies. These findings inform cognitive load management in technical education and suggest directions for broader validation.