to . However, other sizes and types of balls can be used. During regular play, or "classic," the ball must be hit with the player's hands only. In classic play, carrying, catching, or holding the ball during play is not allowed, although putting spin on the ball is allowed as long as carrying does not occur. Prolonged contact with the ball can give players unfair control over the play. Hitting the ball must create a perceptible change in the ball's velocity (speed or direction). Elimination Players may be eliminated from the court because of errors or fouls they commit. Eliminated players leave the court, the remaining players move up to the next highest square, and a new player joins the court in the lowest square. Eliminated players wait in line for their next turn. The following actions may result in elimination (although many variations exist): Failing to hit the ball into another square Missing the ball Hitting the ball into your own square Hitting the ball out of turn Hitting the ball with a prohibited body part Hitting the ball out of bounds (or onto an internal boundary line) Hitting the ball before it touches the ground Game scalability Four square is a popular game for children and school playgrounds. It is possible to scale the game's difficulty and supervision appropriately for different age groups and ability levels. Schools, churches, and camps often change the size of the court, the type of ball, or aspects of the rules to create variation in play or to suit the players' abilities. Similar games Four square has inspired other similar games. One example is nine square where instead of the grid being two-by-two, it is three-by-three. The king court is in the middle and the ball is served from this position. The rules are similar in how the ball is passed between players by bouncing between squares. Other branches of the game have been popularized in recent years which are played on an aerial grid. It is similar to the original in that four or nine people play in their respective spots, but they must keep the ball off the ground like in volleyball. Rotation and rules are similar to each grounded rendition. The game is also similar to Handball. History Four square dates back to at least the 1950s. A game called "four square" is mentioned in newspapers at least as far