Prior to college-level mathematics coursework, students are not routinely provided with the opportunity to engage in the kind of sustained mathematical thinking necessary to solve complex, multistep problems, most likely because of the difficulties that school mathematics teachers face in communicating problem settings and contexts that are motivating and complex, yet ultimately resolvable by students. This paper outlines the theoretical base, development, and preliminary evaluation of anchored instructional environments (videodiscs) being used with middle-grade students to improve mathematical and scientific thinking processes. Discussed are the proactive motivation due to the video-based format including an embedded data design, the de-emphasis on reading due to a familiar narrative format, the discovery-based learning inherent in student-generated problem resolution, the implicitly manageable levels of complexity, and the possibilities for connections across the school curriculum. Initial preinstruction studies on 12 college students and on 12 high-achieving sixth graders induced extremely poor performance results by the sixth graders, which was not surprising both in view of the less than mediocre performance results of the college students, and in light of the realization that students cannot be expected to exhibit skills that have not yet been developed. (25 references) (JJK)