Your kids don't need a gymnasium to get some exercise on a cold winter's day. This version of volleyball can be played indoors without risk to lamp or limb.
To play, first tie a piece of yarn or string across a 10-foot playing area, about 1 foot above the floor. Divide the players into 2 teams and have them set up crab style (faceup, leaning on their hands and feet) in their stocking feet on each side of the string.
Use a coin toss to determine which team will serve first, then have 1 player on that team launch the balloon into the air for a teammate to kick over the string to their opponents.
The teams kick the balloon back and forth, taking all the hits they need to send the balloon to the other side. If one team lets the balloon touch the floor, the other team earns 1 point and restarts the game by serving the balloon from their side. The first team to reach 15 points wins.