Too many activities will bring down the educational level of your child. This should be closely monitored during the school year. Whatever your methods of discipline, consequences, and household management, consistency is the key. When you promise a consequence, follow through. Try not to be influenced by your child's persuasive tactics.
Children consistently test authority.
Be prepared to follow through each time. Results, while not always immediate, will be forthcoming. Children are just that - children. Although they are learning to accept some responsibility, they are not yet adults, and should not be treated as such. Children need to know that their poor choices create consequences.