first grader school behavior

A while back I asked about daily contracts. My son now is on that system, and at times it works. We have a reward system set up at home, so based on how he does at school each day with his behavior, he gets a set amount of time on the computer (after homework). At times there would be blips in his behavior, a bad day here or there, and sometimes we knew why (up late the night before for example- darn basketball practice time). Well, last week, every day was bad, Friday being the worst. And Monday was bad too. Yesterday and today were better. The only trigger I can think of is that Dad started a new job this last Monday. But it was a change of choice, and DS never seemed to ask or care about it. It seems all he really knows is Dad leaves for work everyday; and he's a chemist, so it's not like we can stop in and say Hi to Dad at work. So I wouldn't think this would make him nervous or act out. We talk to him every day about his behavior- the choices he made, where they became wrong choices, what he can do better, etc. But, it is all ultimately in his hands. Control is important for him, so we let him know this is something he controls, cuz he does.We are starting a new reward system today, earning time at the arcade in stages (each day he either gets closer to the arcade, or moves back, depending on the behavior of the day). Hopefully it will help.I have a meeting with his teacher and school psych next week. I guess I am a little nervous. My mom thinks his teacher has it out for him. I think we offer enough rewards at home for good bahvior, but my DS will do what he wants when I can't be there to be on top of him. Isn't that part of what he needs to learn? Anyway, any advice or woords of cheer?