Having been a regualr education teacher dealing with down time -- math
games work. A set of addition, subtraction flash cards could provide a
quick game of around the world. A game that requires no materials is a
variation of a childhood game I played in the car on trips, "My father
owns a grocery store and in it he sells something that starts with the
letter b..." How about My mother owns an art supply store and in it she
sells -- the kids guess by raising their hands. The one who guesses
gets to continue the game.