I don't have any problem with you teaching anyone how to throw the ball properly.
That said, I don't know if you need to teach someone to "hook" a ball. I think that you should just teach them about proper alignment of their feet, good footwork and approach, proper kneebend and leverage at the foul line, clean release and follow through.
Then, take them to a real professional driller and have them properly fit with a good quality ball with a good drilling in it.
If you do all these things correctly, a hook of some type, whether the child be a stroker, tweener, or cranker, will develop on its own.
I don't think teaching a child ( or anyone ) how to hook a ball isn't a good idea, mainly because their technique for hooking the ball may not be the same as yours.
Teach them the basics and the proper execution of them. Then let the hook come to them naturally. That way, it is dictated by the strength and ability of each individual bowler.
P.S. That other "coach" is an idiot. If a child asks you a question, you should try your best to answer it. If you don't, the child may quickly lose interest and move on to something else.
P.S.S. After further review, being as everything was about the other "coache's" kid, maybe they don't want the competition to learn how to hook the ball because their kid can't. Maybe they are afraid they will get beaten by someone who can hook the ball and thusly improve their carry percentage enough to beat her son.
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"TOO SOON THE POWER, TOO LATE THE WISDOM"
