Hi, its always difficult but I think you need to set clear boundaries for your son. At the moment he is flexing his muscles both at home and at school. He needs to be shown a better way to deal with this and as you have said he listens for the first day so obviously some of what you are saying goes in. You will need to keep reminding him of how you expect him to behave and have a consequence to his actions if he does not. Give him a star chart or similar with a clear goal say after 10, 15, and 20 days as a reward. Ask him what he would like the rewards to be ie at 10 days a bag of sweets, 15 days a friend round for tea and at 20 days a trip out somewhere special. On the negative side of this if he has a bad day then you must remove one of his stickers so he goes back down the chart, give him some incentive by starting his reward chart at 3 or 4 stars. You must be firm and not give him stars if he does not deserve them. Get his teacher involved so he/she can pass on information to you about his behaviour at school too. This is very important so you can show a united front. Keep strong and good luck