Spatial ability development is of paramount importance in engineering training, especially for architects. The paper aims to compare results achieved by the world-wide Mental Rotation Test (MRT) at the University of Ljubljana and at the Ybl Faculty of SzIU in Budapest, with respect to total scores, improvement and hand preferences. The paper concludes that the mental rotation aspect of spatial intelligence can significantly be developed by Descriptive Geometry courses in both countries. Sophisticated statistical analysis, however, leads to new ideas in scoring MRT. The main goal of the paper is to present an alternative scoring system, which seems to be fairer and provides the expected statistical behavior of samples.