Kindergartener is in danger of suspension, and I don't know what to do

My kid started kindergarten this year. Generally he's a well behaved kid but he gets over excited during recess/playtime and has trouble keeping hands to himself.The teacher has informed us that his "touchiness" is causing problems because kids will ask him to stop but he will keep doing it. We've had an issue with him not responding to commands at home, not in a malicious sense, but it seems like a lot of times when you tell him something it's like he didn't even hear it. We've been working with the teacher for the last week to try to get him to keep his hands to himself by having her talk with him several times a day to go over his behavior. We also talk to him about boundaries at home. This seems to have helped during in-class activities.Yesterday, we received a note from the teacher that he managed to scratch a classmate and give another one a bruise on the nose during recess. We talked to him, and to the teacher. He's not buillying, but being wild during playtime. They had to record these incidents, and since she's already been working on behavior improvement with him and given that he hasn't responded completely, he's at risk of suspension from school if more incidents occur.I'm at a loss here. I would have never imagined having to deal with possible suspension of a kindergartener. I don't know how to get through to him to stop touching other kids, to be less wild during play time/recess at school. They're also 5 year olds, so naturally kids will be wild and thus will get hurt (either by equipment or from each other).I don't know what to do about the episodes of lack of response to commands. We've done punishments, we've done standard hearing tests. via /r/Parenting http://ift.tt/2g7yRKs