Raising your hand in the classroom is so old school. Thanks to the massive influx of technology into education, there are dozens of new ways students can virtually voice their opinion. From hardware (clickers) to software (Survey Monkey), there’s no shortage of free and cheap ways to get more students talking, thinking, and participating.
http://edudemic.com/2012/04/the-teachers-guide-to-polling-in-the-classroom/