Kids at that age don't really understand the meaning of "ignore".
From her D's point, Ignore means she pretending not getting hurt. She doesn't understand what is keeping peace in her heart. Actually, just pretending to ignore will hurt her D more.
From the mean girls's point, she is too young to understand that the ignore from other side means she should stop because no response will bore her.
And the worst thing can happen, some other kids will learn from the mean kid quickly, they like to copy bad behaviors. they will think her D is so weak, everyone can get a piece of her. pretty soon, her D will become the one being picked on mostly.If this happened, very hard to stop, everyone would think there was a reason why they all pick on this girl.
