The use of physical models in teaching graphic expression in engineering has proven to be an effective strategy for enhancing spatial understanding and visualization of complex structures. This study investigates the impact of using this methodology in the Graphic Expression course in engineering degrees, assessing it by means of final marks comparison and an online questionnaire answered by the students.

The methodology was first implemented during the 2023–2024 academic year and involved using 3D-printed models to support lesson content and practical activities. These focused on essential topics such as orthographic projections, axonometric drawings, cross-sections, and assemblies. After this, a survey was administered to Electrical Engineering (EE) and Chemical Engineering (CE) students during the current academic year. Using a 1 to 5 rating scale, students evaluated the usefulness of these models across different areas of graphic learning (projections, sections, assemblies, etc.) and provided feedback on their overall experience. Results showed average scores ranging from 4.0 to 4.8 out of 5 in all the areas, indicating a positive perception of how physical models facilitate understanding of complex graphic concepts.

Additionally, a comparison between the average grades of the 2023–2024 academic year and those from the previous year (2022–2023) was performed. Results showed that the mean value of the grades obtained in the 2023-2024 cohort (5.44 for EE and 6.10 for CE) were higher than those obtained in the previous course (5.00 for EE and 5.80 for CE) when physical models were not yet used, demonstrating a quantitative impact of this methodology on student performance. The improvement in grades suggests that physical models are an effective complementary tool in teaching Graphic Expression, and that their introduction into additional engineering programs would be beneficial.

Therefore, in the 2024–2025 academic year, the study expanded its focus by applying it to two additional degrees, apart from the EE and CE degrees: Mechanical Engineering (ME) and Industrial Technologies Engineering (ITE), and also incorporating standard components such as bolts, nuts, and springs to enhance normalization and assembly-related content. Results showed similar average scores ranging from 4.0 to 5.0 in all the areas, reinforcing the positive perception of how physical models facilitate understanding of complex graphic concepts. The average final grades for 2024–2025 were: CE (6.86), ME (5.60), ITE (5.96), and EE (4.97). Moreover, 80.19% of students completed the final exam, compared to 69.77% in the previous year, reflecting a notable increase in student participation. The global average grade also rose from 5.71 to 5.86, reinforcing the broader academic benefits of the approach.

These findings confirm the effectiveness of incorporating physical models into the teaching of graphic expression, not only in improving conceptual understanding and academic performance, but also in enhancing student motivation and engagement, as evidenced by the higher exam participation rate.

Keywords: 3D visualization, engineering education, spatial understanding, student perception, teaching methodology.