Since we have small grandchildren. Some of the advice from "experts" was to 1. Stay where you last saw the child. A lot of times they are play hiding. I did this to my mom in a department store once 2. Speak loudly that you have a missing child and provide a description. 3. Recruit families to look for you - they might be more empathetic and less likely predators.

Obviously, if you are in a store or facility with a PA, do that as well. The thing I took away from reading up on this is not rely on coaching your child to remember to follow some instructions you gave them months or years before in a far less stressful environment. There are things the parent should do in these situations.