>>So, what do you tell your 11 year old, or otherwise do, when / if they get teased at school by several other kids?
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>Advice him/her my daugter's way. She said me at once:
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>"Dad, if someone teases me, I override it. That makes it angry and after saw failed tease won't try it again.".
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> In a few other cases my daugter makes a counter-attack. My daugter is a dangerious girl... :)

OTOH, the advice for grownups in my area, when being teased by colleagues, friends or any other group of people they know: help them mock you. They're putting you through the machine - oil the engine so it runs smoother, gets done in less time and... spoils the pleasure. The mockers get their pleasure from the victims attempts to defend itself; the "this is good fun and no need to put up a defense" just bursts the balloon, no fun anymore.