This is a two-year study that will examine science simulation software products (both free and commercial) that are available for grades 6-12 science courses and synthesize the body of literature on student learning in such virtual environments to produce a report that will inform science educators and administrators using and buying middle and high school instructional materials in science. Science simulation software falls into two main categories, virtual laboratories and simulations of phenomena. Virtual laboratories simulate on-screen the experiments that are traditionally performed in real school laboratories as part of biology, chemistry and other science topics. They provide opportunities to use lab materials, equipment, and tools that are designed to mirror those in a real laboratory. Other simulations of science phenomena are used to model things that are not easily observed in real life or where a computer simulation offers other advantages. Simulations may be used to show students scientific phenomena that cannot easily be observed in real time. For example, seeing things in slow-motion (like the motion of a wave) or speeded-up (e.g., erosion caused by a river). Research-based evidence is critical to decision-making for leadership in these contexts, yet the research base is fragmented and there is limited current synthesis and/or meta-analysis is available. This study will fill that gap. For broader impact, the synthesis will provide a balanced consideration of the evidence from the field that is relevant to products available now. It is anticipated that this will be widely used by a variety of groups responsible for the science education of middle and high school students across the nation. The findings will be disseminated throughout the science education community and research community through journal articles, conference presentations and through the publication of a special Knowledge Brief that will be widely distributed.