This is an excerpt from Coaching Youth Volleyball-4th Edition by American Sport Education Program.
Executing the overhand serve can be challenging for young players. To use this serve, a player must be able to toss consistently and must have the strength and coordination to hit the ball over the net using an overhand throwing motion. Since the overhand serve requires more coordination, timing, and strength, you should teach it to players only after they have mastered the underhand and roundhouse serves, or have demonstrated the strength to throw the ball over the net with an overhand motion. The overhand serve, when mastered, is more versatile because it allows for greater speed, power, and control (and better placement) than the underhand serve.
When preparing to serve, the player may stand anywhere along and behind the end line of the court. The player’s feet are in a slightly staggered position with the nonhitting foot forward; the knees are bent, and the weight is on the rear foot (see figure 7.14a). The player’s shoulders are square to the net or slightly open to the sideline. The ball is held in the shelf (or nonhitting) hand at about waist to shoulder level in front of the hitting shoulder. The player’s eyes are focused first on the target, then on the ball.
For the overhand serve, the toss is the key to success. A ball tossed too high, too low, too far in front, too far in back, or too far to either side will force the server to "chase" the toss and move out of proper precontact alignment. To make the toss, the player "lifts" the ball approximately 12 to 18 inches out of the shelf hand when the arm is fully extended. The toss should be in line with the hitting shoulder and slightly toward the net (see figure 7.14b). As the ball is tossed, the player brings the hitting arm back and up so the elbow is high and the hand is close to the ear; the shoulders rotate back toward the hitting-arm side (elbow toward the back wall). As the ball reaches its highest point, the player-keeping her eyes on the ball-swings the hitting arm forward as fast as possible, leading with the hip and shoulder twist (torque), followed by the high elbow, and then the wrist and hand (see figure 7.14c).
Contact is made behind the ball (just below center) using the heel of an open hand or half-closed fist. The player uses a "punching" action with little or no follow-through. This type of contact allows the ball to float across the net (floater), causing some indecision and possibly poor passing by the receivers (the player may also use a wrist-snapping motion with follow-through to produce a ball with topspin). As she makes contact, the player transfers weight from the back foot to the front foot (see figure 7.14d). After the serve, the player should immediately move forward into the court and assume her defensive position.
At times, players may need to use a short step with the lead foot as the ball is tossed to add some additional power to the serve. This step is often used by smaller, weaker players so that body momentum helps add power to get the ball over the net. Stronger players may also use the step to add even more power to their serves. Additionally, this step can help teach players the initial mechanics for the jump serve. When the step is used, the initial hand and body position is the same as for any serve, and the movement on the serve is "step, toss, swing." For example, a right-handed player stands in her stance with the left foot forward, so she will take a short step with this lead foot, toss the ball, and swing.
The jump serve is the most advanced of the four types of serves. When performing this serve, the player must jump into the air (similar to an attack at the net) to contact the tossed ball. The jump serve can add more power to the serve and make it even more difficult for opponents to pass accurately. The jump serve is a difficult serve for young players to master, however, because it involves not only proper mechanics (as in the overhand serve), but also accurate timing for the toss, approach, and jump. Coaches should reserve this serve for players who have mastered the overhand serve and the approach used for attacks over the net.
When learning the jump serve, players need to know that two different ball actions can be imparted on the ball at contact-float and topspin-and that there are specific mechanics for each (as in the standing overhand serve). Additionally, players must remember that the toss is crucial in executing a good jump serve. A ball tossed too low, too far in front, or too far to either side will cause the server to move out of proper precontact alignment.
When preparing to serve, the player should be positioned well behind the end line to allow for a toss and an approach toward the net. The player will jump from behind the end line and land in front of the line (into the court) after contact is made. The player’s feet are in a slightly staggered position with the nonhitting foot forward and the weight on the back foot (see figure 7.15). The player’s shoulders should be square to the net, similar to the ready position for the overhand serve.
For a jump serve that allows the ball to float across the net, a player will most likely use a two or three step approach to help prepare for the jump as the ball is tossed. Performing a jump floater serve is similar to performing a layup in basketball where the ball is lifted up and released on the jump, only the volleyball player will hit the ball with the other hand after the release. For this serve, the toss is lower and the ball is carried longer (held onto until during the final step when it is lifted) and tossed closer to the body than for a topspin jump serve. For a three-step approach, the player steps forward with the front foot (see figure 7.16a), to begin the approach while holding the ball in the shelf hand. After completing this first and then the second step (left, right-if right-handed), and beginning the third (takeoff) step, the player tosses the ball by "lifting" it no higher than 12 to 18 inches above the shelf hand in front of the hitting shoulder while jumping into the air, bringing the hitting arm back with the elbow high and the hand close to the ear. The toss for this serve is slightly in front of the body, as when serving from a stationary position in the overhead serve (see figure 7.16b). Keeping the eyes on the ball, the hitter swings the hitting arm quickly forward, torquing the shoulder, high elbow, wrist, and throwing the hand fast at the ball. Contact is made with the heel of the hand and a stiff wrist (see figure 7.16c) to drive through the back center of the ball to create the "floating" action. After contact, the hitting arm moves slightly through the ball toward the target, freezing with the palm to the target (see figure 7.16d). If using an abbreviated two-step approach for the jump floater serve, the player starts with the first step on the hitting arm side (right foot if right-handed), lifts the ball as she begins the second (takeoff) step, and swings the hitting arm forward as described above.
This is an excerpt from Coaching Youth Volleyball, 4th Edition.