He is only 8 years and you are the parent: is there any choice he has, or was he given this option about attending school? just
lead him by his ear to school and whether he likes it or not, he must be made to go. Now if he not a communicative child, then perhaps he has a problem at school that he may find difficult to discuss with you. Talk to his teacher and find out if there is something at school that is troubling him. If he has friends, talk to them too. If he does not have friends, that could be troubling in itself about the nature of the child. You may then want to check whether he has social problems for various reasons and meet with a child counselor, if the school has not got one. Learning has to be made interesting especially if he is an over-intelligent child. The disobedience will be an attempt to wrest back the control he may have lost when he was younger, or he may have lost his importance, if another child was born recently. The counselor will be able to help with all of these possibilities.