D.T.
You may want to still talk to him once you're home, but no need to punish, just see if he even understands what he did "wrong" and remind him of what he has to do right, remind him in the mornings too. He seems to be having the same trouble my Kindergartner is having. She likes to do things her way, she wants to play when she wants to and the work is "work" and not fun and she gets bored. She usually tells me about the minor infractions herself and we talk about it. For us we have the option of home schooling and it's become (sadly) a bit of a "threat". It however is the truth, if she can't behave and "thrive" in the public system I can and will take her out. This may not be an option for you. What also seems to have worked for us is a daily "reward" for good behavior at school, this week we've had Italian Ice in the freezer that she's been working for. As soon as I notice she's had a full week or two of "good", I plan on switching it up to two days in a row of "good" and a slightly bigger reward and going from there.