I guess I’m old, but it seems to me that back in the 1950s-1960s, kids knew about this stuff by the age of 8 or 9, if not earlier. (I got my first electric shock at about 5, by sticking my hand into a lamp socket. There’s never been a second ;-)
Yeah, sticking a butter knife into a wall outlet gave me the same results that you experienced. A case can be made that kids should have a “jolted” education like that - under supervision, of course.
I did lose a 3 year old nephew due to electrocution.