Parenting Discipline non success

Apparently, there is a punishment worse than anything I can dish out as a parent onto Brett. It doesn't matter if I send him to his room, take a way a toy, or ground him from the Wii. Far worse than any of those punishments is what they dish out from school. Anybody want to know what is worse than what I can do....The WORST punishment that can happen to Brett is to get his binder signed. Thankfully, it only happened once and it was the first week of school. He threw wood chips on the playground and got his binder signed. When he came home he asked me what wood chips were and when I told him about the dirt at the playground, he said to me.. "Oh, we're not supposed to throw those."