I need some

. My 10 year old son is being picked on by an older schoolmate. On the playground, this kid will either tackle my son or put the wrestle moves he knows on him to

him to the ground. One teacher saw this and put the other kid "against the wall" for a week. This was 2 weeks ago. The other night, my son came home with bruises on his arms from this kid. He was back on the playground again. We talked to the principal and he has decided to keep this kid in at recess for an indefinate period of time until he feels that the kid can behave. Now I am really concerned about what will happen when he is back on the playground with my son. Does anybody have any advice about dealing with this bully???