With this the professor periodically presents during his/her lecture some questions for the class to answer. It’s usually presented on some overhead screen, with some detectors positioned on both sides of the room. When the professor finishes asking the question, the students pick the multiple choice answer on their clicker and in a few seconds the results are given for everyone to see. Then based on how well the students did, the professor moves on. If most of the students picked the wrong answer, then the professor goes over the subject matter again.

I purchased mine at the school bookstore, then you have to go to a specific website to register your clicker with the class. Hope this helps.

RE:
Clicker for college classes?
So there's a device that some of you might know…it's called the clicker. It's used to help increase interaction among the professor and the students. Anyone have more information on this device and where I could purchase one at a good price?