This study investigated the effect of Google SketchUp on students' learning achievements in spatial visualization. A quasi-experimental with pre-test and post-test design was used to conduct the research. Eighty-four fifth graders from a public elementary school in Taiwan voluntarily participated in the study. Students from different classes were divided into three instructional modules: Google SketchUp (with full features), Google SketchUp (with limited features), and traditional instruction (hand-held objects). Students in each of the three experimental groups were instructed to manipulate various 3D objects that were created by a class teacher. A criterion test was developed to measure students' understanding about basic concepts of spatial visualization. The educational experiment was completed within three weeks. The results showed that Google SketchUp (with full features) was an effective learning tool to support students in developing spatial visualization skills (F=8.20, p < 0.01).