Aculady is correct. Every place has their own policies ranging from easily worked with to totally rediculous and everything in between.
Does your child have a gifted IEP to bring with you to your new residence? Ours definitely helps during moves at least to back up that we aren't making everything up just for the fun of it.
Do you know the general area you are going to be living in. You could call the school board and see what their policies are on their gifted services etc and see what testing they use/are familiar with. Also they may have suggestions what they need from the losing school to help the transition go smoother.
Moving is no fun, being military we do it all too often and I dread it due to DS's academic needs. I wish you luck!
