This is not a normal behaviour for a 6 year ald. He is acting out something that he has witnessed or done to him.
I would worry about the effct that this behaviour will have on your little girl.
The authorities of the school should be questioned.
Whatever you do please please do not think it is something " normal" that this boy is going through.
Do let the people invloved know what is going on, it shouldn't be dismissed, a 6 year old is old enough to know not to engage in such behaviour, and it could save major upsets if you let someone know.
