Understanding the Teaching and Practice of UML: Insights from Brazil and Portugal

 Context: The Unified Modeling Language (UML) has been a foundational component of software engineering education for decades. However, the increasing adoption of agile methodologies and the emphasis on lean documentation have raised questions about the practical relevance and usage of UML in industry. Understanding the gap between academic instruction and professional practice is critical to improving modeling education and supporting meaningful software design. Goal: This study aims to investigate how UML is currently taught in academic settings and how it is adopted in professional environments, comparing perspectives from Brazil and Portugal. The objective is to identify alignment or misalignment between education and industry needs and provide actionable insights to improve modeling practices.  Method: We conducted two structured surveys: one with 80 instructors from higher education institutions and another with 206 software practitioners. The study employed a mixed-methods approach, combining descriptive statistics for quantitative data and Grounded Theory techniques for qualitative analysis of open-ended responses. Results: The findings show that UML is primarily taught using a subset of diagrams—namely class, use case, and sequence diagrams within traditional Software Engineering courses. In contrast, practitioners report limited use of UML in real projects, often constrained by agile workflows, lack of tool support, or perceived complexity. While educators emphasize UML's value for abstraction and documentation, professionals favor practical communication tools and simplified modeling practices. Conclusions: There is a significant gap between how UML is taught and how it is used in practice. To bridge this divide, modeling education should incorporate agile-compatible strategies, emphasize practical tool use, and focus on diagram types most relevant to industry. These adjustments may foster better preparation of students for the realities of software development and promote more effective use of UML in professional settings.