You can't fix a crumpled piece of paper. (LOM)

''A teacher in New York was teaching her class about bullying and gave them the following exercise to perform. She had the children take a piece of paper and told them to crumple it up, stamp on it and really mess it up but do not rip it. Then she had them unfold the paper, smooth it out and look at how scarred and dirty is was. She then told them to tell it they’re sorry. Now even though they said they were sorry and tried to fix the paper, she pointed out all the scars they left behind. And that those scars will never go away no matter how hard they tried to fix it. That is what happens when a child bully’s another child, they may say they’re sorry but the scars are there forever. The looks on the faces of the children in the classroom told her the message hit home''