My Take
Overall, I really enjoy plickers as a way of interacting with a whole group as it integrates technology, without necessarily focusing solely on it or overshadowing the content. I also enjoy that it gives each student a tangible way to be involved. A few potential obstacles to making Plickers a usable tool might be the need for a computer/projector an device to scan the Plickers. I used my personal cell phone, which was fine except that it tended to drain my battery fairly quickly. This was a greater concern at the secondary level given that the activity would be replicated throughout the day.
Technically speaking, it's fairly intuitive to use, though some initial set-up is required especially if card numbers will be assigned to specific students. Additionally, the actual questions need to be entered into the library, but the ability to organize questions into folders and reuse or edit them is very helpful. An update that would be even more useful is the ability to share questions with other users. This collaborative effort might reduce some of the behind-the-scenes work required to use Plickers with a class.
When I used Plickers to spark discussion, there were no "right" answers, so it seemed there were fewer technical issues. However, when used as a review tool, I did encounter a few occasions when the cards were scanned or answers recorded incorrectly. Another common issue was students keeping the Plicker cards facing forward, which meant that perhaps the camera caught a different choice than they intended. With explicit instructions and practice, this became less of an issue.
While use of this tool limits questions to multiple choice type responses, I see that as motivation to write high-quality questions. One thing I didn't find as intuitive or useful was the ability to transfer the data collected within the Plicker website to another platform. Granted, I could export it as a .csv file or see reports for individual students, but to print that seemed to negate the benefit of using the technology in the first place. Given the few glitches with scanning, I mainly used Plickers in class, but not necessarily for assignments that were scored. One final drawback related to content-specific questions is that some students may be pressured or rushed to make their selection with very little control over strategies such as skipping an unknown question and returning to it later.
Despite some drawbacks, the fact that Plickers are available and free is certainly a benefit to teachers and other presenters.
How I Use It
My first introduction to Plickers was with adults in a professional development scenario. It was a great way to gather information from a large group in a short amount of time. Since then, I have used Plickers with adults, middle school students, and most recently third graders. In middle school, I found this to be particularly effective to collect data, which then drives discussion. The discussion establishes a foundation upon which future lessons and learning will take place. For example, there were ten "Agree/Disagree" statements related in some way to a science fiction novel we would be reading soon. Passing the Plicker cards out at random as well as the discreetly placed multiple choice letters seemed to allow students to be honest with their opinions. Displaying the graph of results and following up with discussion really made the whole activity interactive and thoughtful.
For my third grade students, I found this tool most effective for whole class review lessons. In some ways there was an unintentional formative assessment benefit, in that misconceptions were clarified or lingering questions answered prior to the summative assessment of the unit. With elementary students, they were completely engaged and cheered when the correct answers were revealed.