This study investigates children's spatial cognition in the microcomputer environment created by "HyperGami." Two categories of spatial cognition have been described: spatial visualization, which involves mentally rotating, manipulating and twisting two- and three-dimensional objects; and spatial orientation, which involves the ability to remain unconfused by changing orientations of spatial configurations. "HyperGami" is a computer application which allows students to design, decorate, explore, and manipulate a two-dimensional net made up of polygons and their associated three-dimensional solids. Subjects for this study were 12 sixth- through ninth-grade students in the University of Wyoming Laboratory School. Students were given pretests and posttests. Once a week for a period of 6 weeks, the subjects interacted individually with "HyperGami" for 1 hour. They were divided into three groups, each with different exploration exercises and different aims. In the first group, each subject made gains in their ability to recognize the nets of solids, which require spatial visualization ability. Results from the second group suggest that interaction with "HyperGami" may have helped the subjects improve their ability to visualize the solid from its two-dimensional net. No evidence was found in the third group to show that the hours spent interacting with HyperGami helped the children to count vertices, to count faces, or to identify faces after truncation of vertices. Appendices present the polygon configurations used in the pretest and posttest. (Contains 31 references.) (AEF)