Choose not to shout. This doesn't mean you have to be soft spoken. You can still speak forcefully. But he knows he's hit a button if he gets you to shout.
Structure his life.
a. After supper is homework time. There is no TV, no phone, no games until you have examined his homework. In one boarding school I worked at a kid who was doing badly had a homework book. Teacher had to sign that the the assignment was written correctly into the book so that the duty master could call him on it in study hall. "Math p 103 odd problems" it says. Don't tell me you don't have math homework.
Do this at the dining room table, not in his room.
b. Give him chores to help out the household. Ideally these are things that are done on a regular basis. Washing dishes, sweeping the floor, mowing the lawn, walking the dog. One good idea is a chore jar for odd jobs. Chores should be structured in units of about 5-15 minutes. So "Mow the lawn" is a 4 chore job, and "Trim the lawn" is a 2 more chore points. So he may have 30 minutes of daily chores, and a requirement for 8 chore points a week. He goes nowhere on Saturday until he's done his chores.
c. Don't give him an order that you can't verify. Thus it's ok if he gets home before you to start his homework, but you don't command this, as it's hard to enforce.
- Actions have consequences.
a. He swings at you, you grab his arm, and immobilize it. All people who work in care take courses on handling uncooperative people. There are ways for a petite nurse to keep a big hulk of a man under control. Check youtube if you want to learn on your own.
b. "No!" in your best bad dog voice is a useful tool.
c. Anytime he acts out there is a consequence. Kimberly was a 3 year old who had tantrums. Helen's standard line was, "Go to your room until you can smile." Kim was usually back and bubbly in under 2 minutes.
At age 11, consequences should be immediate. At that age, something that happens next Tuesday isn't very real. Ideally consequences should be linked to the event. E.g. I had a kid who was chronically late to class. So I told him that if he wanted to go home for the weekend he had to practice getting places on time. So during his free time after school, he had to report to me every 15 minutes plus or minus 1 minute. Each time he missed, I added two more report times.
He shouts: Hand him a strip of duct tape. "Put this over your mouth for the next hour, and think carefully before you shout at people." The act of making him put the tape on himself is a way that he is learning to discipline himself.
Put a box in the middle of the room. (A milk crate is great for this.) "Stand in the box until you are calm enough to talk."
If he values his phone, taking it away from him is a viable option. If you think he needs a phone for safety reasons, look into getting a burner phone that can be restricted to only calling certain numbers. Game access works the same way.
- Open the contract negotiation process. We have social contracts all the time, but we rarely speak them out loud. One of them is "I will give you food, clothing and shelter, and hugs. You will be reasonably cooperative, do what your told, and give me a hug back"
At a later age, one good tactic is to go through the process of what it would take to live on his own. This was actually part of a grade 10 course in my school, "Career and Life Management" Part of it was to find a job using the papers and online services, but using only their present education, figure out what they would make, then try to find a place to rent, a way to get to/from work, and what they had left to eat with. Most kids were astounded that even at $16 to $18 an hour (I'm in Canada) they needed a roommate to make ends meet, and there wasn't much in the budget for partying. Part of the course was some basic cooking too, and how to do comparison shopping for food... Made a bunch of headstrong boys somewhat more thoughtful.
So, start out by asking him what he wants. He makes a list -- bigger allowance, stay out late, getting drunk, whatever. Ask him what he needs. This is a longer discussion and involves drawing him out in terms of immediate needs -- food, clothing, shelter, as well as longer term needs -- education, independence. Point out that every freedom has it's price. "I want to be abe to drive so I can go to the mall on my own." This has several prices: Driving responsibly and safely; paying for the car, the gas, the insurance.
Ask him what he things you need. Draw out the notion of cooperation as being a better way to get things done. Ask him what he's willing to do to get the things, and freedoms he wants.
At this age getting him to put himself in your shoes is a tough call, but it's good practice. You want him to realize that one of the things you want is for him to do well in school.
This is a contest of wills. (In the bad old days this sort of behaviour would be met with a spanking, at least until you weren't physically able to handle him. This seems to be unfashionable now, but it makes for polite kids.)
You must not back down. Sometimes it means you leave whatever you were doing: abandon the shopping cart and go straight home. If the two of you have to live on oatmeal for a week because of his tantrum at the supermarket