The purpose of this chapter is to provide educators with a case study of the design, development, and implementation of a Multi User Virtual Environment as a core medium in a high school based blended learning system. Science through Second Life focuses on the opportunities and challenges encountered by educators in the creation and realization of a series of virtual learning environments in Teen Second Life on the topic of environmental sustainability. This chapter considers instructional approaches to support scientific literacy and thinking, the optimal use of multiple media for supporting media literacy growth, and the use of the blended environment to motivate students, gain their attention, and foster a longer term interest in science. Specific examples of learning activities, supportive instructional materials and the pedagogical reasoning are woven into a larger narrative detailing a semester long, 9th grade science class. By reporting the design and development process and the subsequent course of implementation of instructional activities, this chapter provides pre- and in-service teachers and instructional designers with a model of instructional design and practical considerations for developing MUVEs in a blended instructional environment.