I was walking to my vehicle in the Walmart parking lot when I saw a child zooming around her family's vehicle.
Dad was outside keeping an eye on her.
Mom was in the minivan changing a diaper.
The child was very chatty.
So was the dad.
As we parted ways I remembered a piece of advice that had been useful to me when my kids were that ages.
"A stranger is anybody whose last name you do not know."
It is not a perfect piece of advice but it has the advantage of being easy to teach and apply.