I remember when I first started teaching and had students hold up cards to answer multiple choice or True/False questions. This was great, but required me to take a lot of mental notes of who got which questions right and who still needed more support. Plickers is a cool techie way of accomplishing the same thing. Each student has what looks to be a QR code that is assigned specifically to them. Depending on the orientation of the QR code, a student is able to display "A, B, C, or D" or "A" for "True" and "B" for "False". The teacher uses an Tablet or Smartphone to scan the classroom and viola, a response for every student is recorded and stored on the Plickers site.
Want more information?
The website: plickers.com