Okay, I'm gonna give a little advice, but I'm giving it based on my experience with two children who have ADHD in my life. One is my niece who is now 13, they figured out she had it at about 8 years old also. The other is my Daughter's half brother who is 8 now and they found out last year. So please do not take offense to anything I say. I am going by what I have seen and how the parents in these two kids lives reacted, and still react.
Okay the first thing is, my experience with ADHD is, parents and teachers do not take the time to learn all they can about it. They assume the child is just being a brat, belligerent, defiant, etc etc. The problem with ADHD, is they tell you kids just can't pay attention. Have low attention span. In my experience it is not that at all. They can pay attention, they just do it differently. They need to be talked to, not talked at. What I mean by this, is you need to literally get down to their level, look them in the eye and speak to them. If they ask a question it needs to be answered. It isn't them avoiding doing what they are told to do, and it doesn't necessarily mean they don't understand or comprehend what you are telling them to do, they just need to understand the who, what's and why's of it all. If that makes sense. ADHD kids have short attention spans. Which means they can tend to get bored quicker than another child, UNLESS it is something they are really interested in. Then it seems you can not take them away from it, because at that moment nothing else exist.
The other thing is, adults get frustrated much quicker because you just expect them to do what they are told, and then the frustration,anger and sometimes yelling occurs and they block that out completely. It's not hard for them to block things out, so when other people may want to block out someone who is being angry or yelling or just acting frustrated we cant, they can. Which just causes the person to become more angry, or frustrated.
Both the kids in my life with ADHD are extremely intelligent. They ask some questions that I think, why do you even want to know that, or wow, I wouldn't have thought to ask that. But I have noticed if you take the extra 5 or 10 minutes to answer their rebuttal questions as I call them, they are way more likely to do the task set before them. I also have a way with the 8 year old, when he starts asking me questions, I answer the first 3 or 4 then I tell him, Let's make a deal.. if you do what I asked you to do, I will answer more questions. he almost always replies with okay...
The other thing is, children with ADHD, have SHORT attention spans. That means, don't give them a list of things to do. Like, go wash your hands, then come back here and set the table, and don't forget the napkins. They most likely heard something about napkins and that is all. You need to tell them one thing at a time. My niece is constantly tasked with long lists of things and even though she is 13 a list of 3 or four things is to much. for the 8 year old I would do one at a time, go wash your hands and come back here, I have a "project for you" The 13 year old I might say hey go wash your hands then I want you to help me set the table.. Then when they were done, I would say the next thing. Etc Etc.
The problem in schoola is they have way to many kids in a room to be able to focus on one child that has ADHD, the school feels it is not their problem and why don't you put them on medicine, to make their job easier. Not to help the kid, just to make it so they don't have to take the extra time with your child. One thing that has helped my niece extremely is the school she is at now, has a special program which allows her to leave the class room once or twice a day and have one on one with certain subjects, such as math and reading. She is actually passed her class now on where they are. Her grades have increased significantly and she actually almost likes school now. She was the one who would be kicking and screaming getting on the bus, and spent all day in the nurses office lol, just to get out of class.
I just realized I wrote much more than I planned on. These are just a couple of things, I have noticed and a couple of things that work in these two kids lives. I hope you don't take offense to any of it, and maybe some of it will help.