This project investigated and documented how, and in which circumstances, technology-enhanced curricula allow students in grades K-6 to engage in learning challenges and experimentation that support the development and application of important geometric concepts and principles. The project focused on a subset of geometric thinking: units, patterns and repetition; transformations of shapes; and similarities and symmetries. These ideas underlie understanding of many of the topics traditionally taught in elementary geometry and form the basis for understanding of other topics in mathematics, science, and the arts. The technology-enhanced curricula that were the focus of the research include specially designed software that helps students use and learn mathematical ideas. The research took place in classroom contexts that integrated several elements individually associated with improved student learning: software-based activities, concrete manipulatives, activities supporting a variety of learning modalities, examples and applications from students' daily lives, and effective instruction by knowledgeable teachers. The project was a collaboration among investigators from three institutions- Education Development Center (EDC), Inc., University of Wisconsin, and State University of New York at Buffalo. The three partner organizations worked together to develop and implement a coherent research design across all research sites, and offered equivalent training and ongoing support for the 12 participating teachers. EDC provided overall management and coordination for the research effort.