[glddstgpsy]

I need some advice regarding a proper reward system. Our son (7) is having problems listening and taking his time, both in school and at home. In school, he doesnt follow directions very well, is quick to finish his work and puts very little effort into his work at school. With his homework, he is much better, but during school his teacher gives the class independent time to complete worksheets. He rushes through these, not reading the directions on the top of the sheet, and turns in sloppy work. His tests are not better either. It seems as though he wants to finish just so he can play with the other kids. I sometimes wonder if he thinks its a race to try to finish his work first!
At home, we have to ask him several times to do something; he is bad at following instructions. He is a wonderful child otherwise, kind, gentle, and lots of fun! However, I would like to implement a reward system for him to encourage listening the first time we ask him to do something. He loves to play video games, and as of today when he brought home an F on his math test, he has lost that privelege. I was thinking of something like pennies in a cup, and if he gets 10 pennies (10 times of listening without being asked more than twice) that he gets to play a game for half an hour or so. I have read many strategies for this, but I would like a little advice on what exactly would be a good reward system for him.
Also, I would like any suggestions that anyone would have regarding the school issue. Its hard when we are not there!
Thank you!