The most common fear in 6 year olds, if I remember my child
   psych classes from way back when, is death. A little girl named
   Michelle in my class got hit by a car and killed when I was in
   Kindergarten/1st grade, and apparently I was inconsolable for a
   long time over that whenever I'd think about it. I think it's
   the age when we can really begin to grasp the depths of it and
   what it really means. Kids are older than we think they are.
   They do a lot of pretending-to-be-happy for our sake. Of course
   they're also happy too, but kids don't like to see adults
   upset... until they're pre-teens.. then they kind of enjoy it.