This study describes two efforts: (1) the development of a learning environment that includes a hypermedia data base about Mesoamerica, and (2) an observational study of middle school students using the system within a framework of problem-based learning for mastering content and thinking skills. The goal was to create a learning environment influenced by metacognitive strategies, hypermedia interface design, and problem-solving scenarios preceded by discrepant events. Participants consisted of 25 seventh-grade social studies students. They were divided into four groups, each having access to a microcomputer with the hypermedia data base. They also had additional resources such as books and magazines dealing with Mesoamerican civilizations. Data collection included direct observations from four facilitator/evaluators, audiotape, videotape, student products, software routines, and questionnaires. Findings suggest: · the hypermedia data base navigation was usable and easy to learn for these students · a discrepant event inquiry model was among the factors contributing to sustained student activity · embedded problem-solving strategies facilitated higher-order thinking only when coupled with teacher support. The key in the environment appeared to be teacher-student interactions which allowed the teacher to dynamically assess students' abilities, then provide necessary support for independent action. The computer's role was that of a tool which mediated between the teacher and students. / Ph. D.