I just used a free online audience response tool to pose questions to my high school journalism class. The students used their cell phones as "clickers" in order to respond to my survey which was projected from the computer in my classroom. It worked great! We not only were able to discuss the answer to the content question (formative assessment), but we were also able to discuss the use of the application in school settings. Not all of the students participated--I warned them upfront that if they did not have an unlimited texting plan from their provider that it would cost them a text message fee.
Online address...
http://www.polleverywhere.com/
