The blindfold walk is a simple enhancement to normal question and answer time that many teachers do at the beginning of class. Close your eyes and/or wear a "blindfold" and walk around, trying to touch students on the head. When you find a student, open your eyes and ask them any kind of review you may be working on at the time. You may need to tell them that they are not allowed to move, or you will be hard-pressed to actually find anyone. This activity will not work well with all classes, but students generally enjoy watching you be funny for a bit and it gets the class in a good mood and ready to go on to the rest of the lesson.
See more information about how to get started at the Central Wikia tutorial.