Tricky. JK-1 means junior kindergarten to first grade, does it? (I'm not from the US.) So you don't have the option of just accelerating him within the same school. What happens to children with CP like your son's after 1st grade? Could that school help or advise, or could he go there early (maybe not right now, but some time soon?) There is a child with CP at my son's school, apparently doing fine - I think there is a nurse based there involved, I'm not sure exactly how it works - but I realise it has many variants and degrees and not all children would be able to be in a mainstream school and still get the therapy they need. At the least you obviously need to have a talk with his teacher about the fact that he's finding the work too easy.
You may find it useful to hang around (here and maybe also at the Well Trained Mind forum) and read about what people are doing in the way of "afterschooling" and providing interesting extra things for children to do. Yours is only 4 - whatever he does needs to be pretty much play, and maybe that will help the school to be accepting? Logic puzzles, picking the level so that he finds them tricky but not impossible? Is he reading, and if so what and how much? That's another area that's very easy for school to differentiate, if they are willing.
Welcome!
