During the past decade, members of the Cognition and Technology Group at Vanderbilt University have worked with hundreds of teachers and thousands of students throughout North America in the context of the Adventures of Jasper Woodbury problem-solving series--12 videodisc-based adventures plus video-based analogs, extensions, and teaching tips designed to improve the mathematical thinking of students from grades 5 and up, and to help them make connections to other disciplines such as science, history, and social studies. The experience of developing the Jasper series, testing it in classrooms, and re-designing it based on feedback provided The Cognition and Technology Group at Vanderbilt with extraordinarily rich opportunities to learn from teachers, students, parents, administrators, and other community members. This book was written for two reasons. First, it helped the authors to organize the thoughts and experiences of over 70 members of the Learning Technology Center who worked on the Jasper project, and to collaboratively reflect on their experiences and relate them to the broader literature in cognition and instruction. Second, this book gives others a change to learn from the experiences of the Cognition and Technology Group at Vanderbilt. The book is anchored around their experiences with Jasper, but the issues explored are relevant to any attempt to improve educational practice. This book tells a coherent story that helps readers explore issues of curriculum, instruction, assessment, and teacher learning (professional development) within a single context (Jasper) and how all these topics are interrelated. It also helps readers see the relevance of research programs for improving educational practice. Throughout, the need for maintaining a balance of laboratory and classroom research is emphasized.