Re: Advice needed!!!
Did you take any time to deschool? He might do better if he had a good break to just relax and be a kid without any guided learning at all.
Beyond that, there are lots of ways to help kids focus. Have him chew gum while he's working. When he gets fidgetty, have him do jumping jacks or run around the outside of the house. Set up some rules and stick to them. In our house, for example, there is no electronic time unless schoolwork is finished at a certain time.
Also, 3 hours sounds like a lot of work for that age. My 11 yr old can usually finish her work in 3 hours. Maybe at this point he would do better if you covered the basics and maybe alternated other things. For instance, do math and language arts, but then alternate science and history, either by day or week.
And what type of learner is he? Does he need workbooks instead of hands on, or hands on instead of workbooks, or something else?
I don't see the point in sending him to school for something that you could just as easily work on at home.
Oh, and one more thing -- check his diet, if you haven't already. When my oldest has any artificial colors and sweeteners, she has a much harder time focusing.