I have dealt with ADHD since a young age. I was finally prescribed medication my freshman year of high school, which made all the difference. Dealing with that medication, however, was its own battle. None of it comes with instructions. I simply learned by trial and error, adapting to each situation and trying to make it work. I would be happy to provide some insight that I've picked up along the way. Feel free to reach out!
I would first ask, what grade(s) are they in? Are they prescribed medication? What is their learning environment like? These questions hold the key to addressing it properly.