How are your finances? I don't know what finished middle school equals for maths but if he has done algebra he could maybe do some of the AOPS courses that go outside what seems to be the US maths sequence. If you have the money there are heaps of optilons. If you don't you need to be more creative. I would require something from maths, science, writing and PE plus reveiw if he has been doing a language. The don't have to all be every day or even concurrent just keep the momentum.