Classrooms of 30 to 300 students, although commonplace, provide poor learning environments in schools and colleges. Active learning significantly improves on traditional methods. With low-cost classroom communications systems (CCSc) every student can engage actively in learning, but results are not guaranteed. Teachers must learn how to use CCSs' as pedagogical tools. Objectives: provide substantive data on the benefits of CCSs in various educational environments; show how CCSs can be adapted to various pedagogies to enhance the effectiveness of the learning environment; quantify the effects of these adaptions on student performance. Research: Scientist-teachers from eight national programs will test Classtalk CCSs' capabilities in research classrooms. Feedback from pilot research at these test- sites will help optimize the tools and interface. In the principal effort, test-site researchers will do controlled evaluations of CCS impact on their own pedagogical frameworks. Anticipated Results: We will learn how to use CCSs effectively under various classroom pedagogies and what software tools make CCSs maximally effective Applications: Successful CCSs are cost-effective tools enabling all students to engage actively in learning. CCSs help identify students' preconceptions and diagnose fundamental misunderstandings. CCSs may incorporate video and other technologies, improve students' motivation, and help teachers to track and assess student learning.