One of the bigger debates in implementing a CRS is on what type of technology the keypads use to transmit the student responses to the instructor computer.  There have been two main types, infrared (IR) and radio frequency (RF).  Recently Web-enabled systems have also begun to show up.

Of course, each technology has pros and cons which become amplified when considering a campus-wide solution.

IR       

    Pros:    good for small groups, won't affect other classrooms, less expensive than RF systems, no interference problems from common wireless equipment like cell phones, Wi-Fi, radio broadcasts, etc.                                                               

    Cons:    limited line-of-sight range, interference from fluorescent lighting, difficult for student to tell if response was received.

RF      

    Pros:    better reliability, farther transmission range, response received acknowledgement, faster response collection.                                   

    Cons:    more expensive, interference with nearby classrooms,

Web    

    Pros:    utilizes existing network infrastructure, web-based, hardware independent.                                                               

    Cons:    requires student to have some type of web-enabled device, too new for much data.

Keypad technology comparison -