M.R.
Smart and the ablity to supress an impulse are completely different and mutually exclusive skills. If you put the great athlete Tiger Woods on the Football field, and then take away his TV time because he did not win, it will not help him to be a better football player. Your son needs instruction and opportunity to practice being in control of impulsive behaviors in combintatin with an anyalsis of what is really going on. If this is nothing more than the garden variety of a boy in class being on the late side of this kind of control, then just reinforce the structure of school at home, and instead of punishing the bad days, reward the good days and ask him what he did to avoid the impuslive behavoirs that day. If he really is just learning this skill, then you will still se results as he gains control without making a major deal of it at home with a drastic punishment.
If this is not a garden variety impulse control issue, and you are really seeing your teacher documenting a nuerological issue for you, then if you punnish his behavior that he cannot control because of a nuerological issue with out dealing with it appropriately, then he is not going to learn anything other than he is being punnished for something he cannot seem to control on any relaiable time table. Additionally, kids with this kind of impairment need concequnces applied imeadiately, or they are ineffective, so your punishment later will not apply to the behavior you desire to reduce anyway.
I did not get the impression from your post that your son has a major issue, but I would be at school finding out if the teacher is over or under documenting. The Humming is a flag for me, and I would not be thinking ADHD, I would be leaving that to a professional based on what you see, if indeed you needed any kind of assessment. That is the first condition that parents and teachers think about with impulsive behaviors, but humming is just not a typical thing you hear about, and I certainly hope that humming is a one time thing.
If he is bored because he is very smart, that is not a neurological issue. Some children who have very good skills have behavior issues because they have relative weaknesses between thier intelectual function and thier soical function, or, may have a relative weakness between thier verbal ablitlies and thier motor ablities, so every time they do something in class where they have more average skills, they feel less acomplished, loose track of thier focus, and missbehave. That is not a nuerlogical problem, but may look the same. If you really think that your son has a problem with this kind of behavior, you need to know if he has a nuerological disfuction, or a relative weakness in relationship to very, very advanced skills. Both issues are only able to be delt with if you get a good educational or nueropsychological evaluation.
I am not getting that you are at the point where you need to do that yet. I would rule out that he just needs a few weeks of direct feedback from the teacher about the new second grade behavioral expectations before I jumped that conclusion. The only way you can know that for sure is to observe the class, talk to the teacher, and not over react to his color and face card while he is learning, so he feels safe enough to make progress.
M.