In schools, learning spatial geometry is usually dependent upon a student's ability to visualize three dimensional geometric configurations from two dimensional drawings. Such a process, however, often creates visual obstacles which are unique to spatial geometry. Useful software programs which realistically depict three dimensional geometric objects and allow their manipulation have been developed and used. The positive impact of such simulations on learning outcomes has been reported. However, to date, very little research has been directed toward studying "how" students learn from such programs. We carried out preliminary qualitative research aimed at documenting what high school students did and why, as they dealt with three dimensional geometry problems represented by a 3D software program. We found that students with relatively low spatial ability skills use the software's tools much more than good visualizers, primarily for making measurements. Students with relatively high spatial ability skills use the software sparingly, primarily to rotate the geometric objects. The activities carried out by the students may be explained in terms of cognitive load reduction. (Contains 3 tables and 4 figures.)