Split up the students into 2 teams, sitting in chairs facing each other on opposite sides of the room. When the game leader yells GO, all of the students must run the the opposite side of the room and find a chair to sit in, and they may not sit in the chair directly across from them. As soon as the students stand up to switch sides have a leader remove 1 chair from each side. Continue playing and removing chairs until you have one person left on each side.
The game gets crazy when students run into one another in the center, but keep an eye on things or it can get rough quick!