I would definately check out the laws in any states I'm considering moving to prior to the move. Have you been to www.hslda.org ?? I'd also check out the vaccination exemptions for the state if that is an issue for you.
Here is a link to the laws for PA http://www.hslda.org/laws/default.asp?State=PA
Your 5 year old is below the compulsory attendance age for PA (which is 8).
Here is a link to the laws for PA http://www.hslda.org/laws/default.asp?State=PA
Your 5 year old is below the compulsory attendance age for PA (which is 8).