to make your transition as smooth as possible, try to get photos of where you'll be moving to....for example, you might be able to get a photo of the local library or the town hall.....you could also let them know that even though the place they are living is going to change, some things will still remain the same-for instance, you'll still go grocery shopping on Wednesdays, or they'll still take a nap after lunch..........you also need to let them know about the things that will change , but possibly for better- for example, your son will now be able to have his own room...or the kids will be able to play outside more because the area is more rural.