This study aimed to develop a collaborative and manipulative virtual Tangram puzzle to facilitate children to learn geometry in the computer-supported collaborative learning environment with Tablet PCs. In promoting peer interactions and stimulating students' higher-order thinking and creativity toward geometric problem-solving, we designed a collaborative Chinese Tangram activity with problem-solving learning strategies. Participants are 25 6th graders of a suburb elementary school of Tai-Chung City. The results suggest that children's competency in rotation and space of shapes had been improved and the scores gap between lower and higher achievers had been narrowed. Such a collaborative Chinese Tangram activity may facilitate peer negotiation, enhance children's belief toward problem solving, and benefit each child to share resources, and a positive interdependent learning context can naturally be developed. (Contains 6 tables and 12 figures.)