Classroom response systems (CRSs) can be potent tools for teaching physics. Their efficacy, however, depends strongly on the quality of the questions used. Creating effective questions is difficult, and differs from creating exam and homework problems. Every CRS question should have an explicit pedagogic purpose consisting of a content goal, a process goal, and a metacognitive goal. Questions can be engineered to fulfil their purpose through four complementary mechanisms: directing students' attention, stimulating specific cognitive processes, communicating information to instructor and students via CRS-tabulated answer counts, and facilitating the articulation and confrontation of ideas. We identify several tactics that help in the design of potent questions, and present four "makeovers" showing how these tactics can be used to convert traditional physics questions into more powerful CRS questions.

Classroom response systems (CRSs) are a promising instructional technology, but most literature on CRS use fails to distinguish between technology and pedagogy, to define and justify a pedagogical perspective, or to discriminate between pedagogies. Technology-enhanced formative assessment (TEFA) is our pedagogy for CRSbased science instruction, informed by experience and by several traditions of educational research. In TEFA, four principles enjoin the practice of question-driven instruction, dialogical discourse, formative assessment, and metalevel communication. These are enacted via the question cycle, an iterative pattern of CRS-based questioning that can serve multiple instructional needs. TEFA should improve CRS use and help teachers ''bridge the gap'' between educational research findings and practical, flexible classroom strategies for science instruction.

The purpose of this study is to uncover and understand the factors that affect secondary science and mathematics teachers' initial implementation of Technology-Enhanced Formative Assessment (TEFA), a pedagogy developed for teaching with classroom response system (CRS) technology. We sought to identify the most common and strongest factors, and to understand the general process of how teachers adopt TEFA. We identified ten main hindering factors reported by teachers, and found that time limitations and question development difficulties are reported as the most problematic. In this paper we provide five vignettes of teachers' initial implementation experiences, illustrating different courses that TEFA adoption can follow. We classify our ten factors into four groups: contextual factors that directly hinder teachers' attempts to implement TEFA (extrinsic type I); circumstances that affect teachers' teaching in general (extrinsic type 0); gaps that teachers have in the knowledge and skills they need to adopt TEFA (intrinsic type I); and ways of being a teacher that describe teachers' deeper perspectives and beliefs, which may be consonant or dissonant with TEFA (intrinsic type II). Finally, we identify four general categories that describe the teachers' initial TEFA implementation.

Technology-Enhanced Formative Assessment (TEFA) is an innovative pedagogy for science and mathematics instruction. The 'Teacher Learning of TEFA' research project studies teacher change as in-service secondary science and mathematics teachers learn TEFA in the context of a multi-year professional development programme. Applying cultural-historical activity theory (CHAT) to the linked activity systems of professional development and teachers' classroom practice leads to a model of teacher learning and pedagogical change in which TEFA is first introduced into classrooms as an object of activity, and then made useful as a tool for instruction, and then-in rare cases-incorporated into all elements of a deeply transformed practice. Different levels of contradiction within and between activity systems drive the transitions between stages. A CHAT analysis suggests that the primary contradiction within secondary education is a dual view of students as objects of instruction and of students as willful individuals; the difficulties arising from this can either inhibit or motivate TEFA adoption.