Having heard numerous well-meaning, kind, smart parents complain about their children's sloth, poor grades, defiance and anti-social behavior, I offer my heartfelf condolences and there little suggestions.
1. If your child is floundering in school or with home responsibilities, give structure, opportunity and praise. Set up some choices of tasks, some of which may be funny or inviting, then make the chosen one very specific, fairly easy (at first) and give good feedback and praise when it's done. Start small and gradually work up.For example, rather than "get ready for bed," there's "brush your teeth, put on the new silly pajamas, or do your bubble bath, first. " One step at a time.
2. Praise profusely but not falsely, especially pointing out effort, improvement and tasks well done. Also, give reputation-changing comments (my term), such as "Playing with your sister shows me what a friendly brother you are becoming," "That good homework impresses me because I see that you are good at knowing science stuff." Once the child hears the new rep often enough, it forms a home in the brain and grows.
3. Share your feelings rather than your outward critical judgment. Say "I am irritated when I see the dirty dishes strewn all over the kitchen," rather than "You pig. Can't you ever clean up?"
4. Brainstorm to solve problems. Sit down with tablet (electronic or paper) and all of you suggest solutions, which you write down liberally. Then, review each possibility, cross out the ones someone can't live with, and come up with a compromise. For example, the child suggests that you always feed the dog, you suggest she does, Dad suggests you all take turns, you suggest allowance depends on the child doing it every day, etc.. In that case, whatever you all decided gets reviewed and maybe revised next week.
5. Give consequences which make sense, rather than punishments. Opportunities to learn and improve work better than making the child feel rotten. The privilege which is abused is the one lost, not something irrelevent. If the kid was on the phone all evening, instead of doing homework, the phone is gone temporarily, not the TV. If the sleepover turned into a brawl, there's no sleepover for quite a while, not withdrawal of sports. Some consequences are a surprise. Fighting with sis gets the consequence of having to do sis a favor, rather than just separation. Talking back to mom means you have to play a friendly game with mom or help mom cook. Although it sounds counterintuitive, it builds the relationship, making bonds strong and less likely to be abused later.
There's more where all this came from . Experiment, enjoy, and be creative.