how do i teach 9 and 10 year olds to serve

how do i teach 9 and 10 year olds to serve

Try coaching the movement in stages, starting with a basic underarm throw (attached) and then then gradually increase the distance.

Start with just an underarm throw, then an underarm hit over the net and as players grow in confidence move onto an overarm hitting technique).

Kids this young have not developed strong shoulders yet. make sure you use a volleylite ball only. Another item is to start with a side arm serve like a baseball bat. They can get more distance on the ball. Over head serve can damage the rotater cup area if you use a regular volleyball. Start them all doing push up at home. have them keep a chart of their progress and reard them for reaching goals set by them and not the coach.

I agree with Alex. Start them with tossing or throwing the ball. When they get to the point of hitting the ball start them at the 10ft. line and work them back. 

A "side arm" serve to me sounds like what I call "chicken wing", which is when player is too lazy to move their feet and just reach 1 armed to make contact during play. Which in my mind would be more damaging to shoulder then teaching proper techique. Tossing progressing to hitting is best way to go.

Start with footwork.  Feet shoulder width apart, left foot slightly in front, balanced.  Show then how to transfer their weight from back foot to front foot.  This would be used for underhand or overhand serve.  Use lightweight vballs and move to 10' line.  Stiff wrist, elbow higher than ear, fingers pointed to sky, laser light in palm that points toward target entire swing.  Teach to start draw back, toss and step at same time.  If ball is a face, they want to make contact on the mouth of the ball.  Follow through to their pocket.  Keep shoulders and hips square to net when they finish.  If they have the strength to serve overhand, let them.  If not, show them underhand for games but work on both in practice.