This article describes an innovative hypermedia product for sixth graders in space science: Alien Rescue. Using a problem-based learning approach that is highly interactive, Alien Rescue engages students in scientific investigations aimed at finding solutions to complex and meaningful problems. Problem-based learning (PBL) is an instructional strategy proven to be effective in medical and business fields, and it is increasingly popular in education. However, using PBL in K-12 classrooms is challenging and requires access to rich knowledge bases and cognitive tools. Alien Rescue is designed to provide such cognitive support for successful use of PBL in sixth-grade classrooms. The design and development of Alien Rescue is guided by current educational research. Research is an integral part of this project. Results of formative evaluation and research studies are being integrated into the development and improvement of the program. Alien Rescue is designed in accordance with the National Science Standards and the Texas Essential Knowledge and Skills (TEKS) for science. So far Alien Rescue has been field-tested by approximately 1400 sixth graders. More use in middle schools is in progress and more research on its use is planned.