Plickers are another way to collect informal feedback from students. Each student holds up a card with a 5 by 5 grid with some of the cells shaded. (Really only 12 of the squares on the perimeter matter). The teacher scans the classroom with a cell phone or tablet running the Plickers app. Based on the orientation of the card the Plicker app recognizes which student is answering and whether the student is answering A, B, C, or D. To get student recognition you enter which student has which card ahead of time.
I tested the 2 cards to a page with some colleagues in the hallway. My phone could read multiple cards at around 30-35 feet. Walking across a standard College classroom it read all the cards I had a class hold up before class one day. Plickers can display the responses as a bar graph similar to other polling software. I plan to test this feature with my Precalculus class next week.
Plickers offers up to 63 cards with its free version. If I have thought about how these work correctly there should be 1008 possible Plickers cards. I imagine that this will be a way they can begin to charge for extra services. They promise basic Plickers will remain free even as they offer enhancements for a fee.