The relative positions of the sun, moon, and earth, their movements, and their relationships are abstract and difficult to understand astronomical concepts in elementary school science. This study proposes a three-dimensional (3-D) virtual reality (VR) model named the "Sun and Moon System." This e-learning resource was designed by combining Microsoft Direct3D Library, C++ programming language, and Autodesk 3 Ds Max for constructing models. This learning environment provides a way for teachers to integrate information and technology into their science teaching. Furthermore, this study explored how teaching with the "Sun and Moon System" affected 128 Taiwanese fourth-grade students' science achievement. Four classes were randomly divided into comparison and treatment groups. The results show that: (a) students in the treatment group achieved significantly better grades than those in the comparison group under traditional class instruction and (b) the questionnaire results revealed that more than two thirds of the treatment group liked to use the 3-D VR model and would like to introduce it to their classmates. Based on these positive results, we are encouraged to develop more 3-D VR learning environments.