This paper describes the application of problem-based learning (PBL) design principles and the inclusion of teacher and study scaffolds to the design and implementation of a hypermedia-based learning unit for the upper elementary/middle school grades. The study examined the following research questions: (1) Does hypermedia-based PBL represent an effective instructional strategy for upper elementary/middle school students?; (2) What are student and teacher attitudes toward the PBL instructional unit?; and (3) How are student and teacher scaffolds utilized during implementation of the PBL unit? Results suggest that PBL may be an effective instructional strategy for gifted and talented sixth grade students. Student scaffolding did not seem to impact achievement or student attitudes; however, teacher scaffolding appeared to increase teacher effectiveness, confidence and attitudes. Three figures include: the hypermedia student interface, resources menu page, and balloon design strategic scaffold. Two tables provide the mean student attitude scores for the two trials conducted. (Author/AEF)