9730438 Gerace Assessing to Learn is a technology-based assessment system for high school physics that integrates formative assessment and instruction. The assessment items are consistent with constructivist and active learning pedagogies; they take account of research into physics education including the elucidation of student preconceptions. Students evaluate their own learning and teachers are guided to tailor instruction to meet student needs. The Classtalk system, a classroom software tool, provides an integrated package that allows presentation of the items for class discussion, collection and storage of individual student responses and a display of total class responses. The combination of sound assessment and immediate feedback results in teachers changing practice to adopt a more responsive instructional style and matching the assessment to the goals of physics education - understanding of physics concepts and the process of inquiry, and application of those concepts to engage in problem solving. The assessment items cover mechanics, electric and magnetic fields, circuits, waves, optics, and modern physics. The project is a collaboration of the PIs, teachers from high schools, Better Education, Inc. and Texas Instruments. Products include the assessment items and accompanying teacher aids that identify the reasons for common student responses and give guidance on follow-up activities and discussion. The extensive evaluation provides information on student achievement, change in teacher practice and on the development process.