Successful attack mostly depends on the setting and this exercise teaches the cooperation between setter and attacker.
It is a game played on proper courts for three-to-three or four-to-four, depending on age of players. Player from team A serves or throws the ball into the opposite side, initiating a play. 1 point is granted for team that makes an attack but only after overhand set directed to spiker. Team scores next 1 point when the ball falls outside the lines after the attack, 2 points when it is defended and 3 points when lands directly on the opponent’s side. Teams take turns with serving (throwing) the ball, no matter which one won previous action. Rotation follows after every completed action.
To make the game easier for younger or less skills players you can also grant points if the third contact with the ball was just putting the ball into the opposite side with the fingers (putting the ball over the net using a forearms passing motion is to maintain the continuity of the game and for this act points are not granted).
To make the play more demanding for older or higher skills players you should play two-to-two on the same courts and require players to set the ball only by overhand motion. The another way is to make rotation as the ball was putted (attack) into the opponent’s side.
source: Akademia Polskiej Siatkowki