Classroom Response Systems

Essentially, a classroom response system (CRS) is technology that:

  • allows an instructor to present a question or problem to the class;
  • allows students to enter their answers into some kind of device; and
  • instantly aggregates and summarizes students’ answers for the instructor, usually as a histogram.

Most response systems provide additional functionality. Some additional names for this class of system (or for subsets of the class) are classroom communication system (CCS), audience response system (ARS), voting machine system, audience feedback system, and — most ambitiously — CATAALYST system (for “Classroom Aggregation Technology for Activating and Assessing Learning and Your Students’ Thinking”).

UMPERG has been teaching with and researching classroom response systems since 1993. We find that the technology has the potential to transform the way we teach science in large lecture settings. CRSs can serve as catalysts for creating a more interactive, student-centered classroom in the lecture hall, thereby allowing students to become more actively involved in constructing and using knowledge. CRSs not only make it easier to engage students in learning activities during lecture but also enhance the communication among students, and between the students and the instructor. This enhanced communication assists the students and the instructor in assessing understanding during class time, and affords the instructor the opportunity to devise instructional interventions that target students’ needs as they arise.


A CRS is, of course, just a tool. How effective one is depends on how effectively it is being used, and what it is being used for. This raises the general issue of CRS-based pedagogy.

Several different flavors of CRS-based pedagogy have been developed and publicized. While they have certain elements in common, they also have significant differences.

Peer Instruction

Developed by Eric Mazur at Harvard, in the context of teaching physics, Peer Instruction is perhaps the best publicized model of CRS pedagogy, to the extent that merely using CRSs is sometimes called “doing peer instruction”. The model punctuates relatively standard lecture with instances of CRS use, as described by Mazur’s web site:

Lectures are interspersed with conceptual questions, called ConcepTests, designed to expose common difficulties in understanding the material. The students are given one to two minutes to think about the question and formulate their own answers; they then spend two to three minutes discussing their answers in groups of three to four, attempting to reach consensus on the correct answer. This process forces the students to think through the arguments being developed, and enables them (as well as the instructor) to assess their understanding of the concepts even before they leave the classroom.

Further information:


Technology Enhanced Formative Assessment (TEFA) is the rather clumsy name for the rather rich pedagogical model for CRS use that my colleagues and I (especially Bill Gerace) have developed. Unlike most approaches, in which CRS use is injected into relatively “normal” instruction, we invert things: A CRS-mediated question “cycle becomes” the organizing pattern of classroom activity, with whole-class discussion carrying the primary burden of furthering student learning. The teacher injects “microlectures” here and there, when a need becomes apparent and a context has been created for students to receive it productively.


By Me & Colleagues

By Others

  • Fies, Carmen and Marshall, Jill (2006). Classroom response systems: A review of the literature. Journal of Science Education and Technology, 15(1) 101–109.

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