9725524 Horwitz Over the past several years, with support form the Applications of Advanced Technology Program of NSF, we have developed and evaluated a series of computer applications that offer a new paradigm for educational software, the computer-based manipulative (CBM). The CBM is an open-ended environment consisting of linked representations and affordances that reify an underlying model and enable students to investigate scientific and mathematical concepts via direct manipulation and experimentation. One of our most successful CBMs has been GenScope, which helps students reason about genetics at multiple levels. We propose to broaden the scope of this technology by creating three additional CBMs dealing with tissues, cells, and molecules. These new applications will interact with each other and with GenScope, to form a seamless exploratory environment within which students can investigate phenomena spanning subdisciplines that are taught separately in the traditional biology curriculum. To achieve such interoperability will involve advanced research in component software technology. We will design and publish protocols and standards for inter-component communication that will make it possible for future developers to create CBMs of their own and link them to ours. Working in urban and suburban schools, we will conduct formative research to determine the optimum use and educational effectiveness of this new technology.