The first group is the one I work with at the Study Center and consists of about 8 kids between 3rd and 6th grade. It is a mix of boys and girls, all from Brooklyn.
The second group is my regular gaming group and consists of four guys, ranging from their mid-twenties to mid-thirties, from all over New York City.
Observation and Speculation
The mysteries I provide for each group are not all that different in complexitiy or depth. Though the groups are very (very) far apart in age, I don't dumb down my connundrums much for the younger group or create overly complex and nuanced ones for the older group. Perhaps a little more of the latter once in a while but not in a significant way.
The younger players take a lot of notes (or at least most of them do) and look at each clue or element and put together what's happening pretty quickly and easily.
The older group, especially one player in particular, tends to lean toward speculations after their observations. That is, they will look at the clues, identify what they know and then spend 20 minutes or so speculating on what else might be involved but there has been no evidence of. This quickly leads to unwarranted assumptions, missing other key details, confusion and often putting the players in a bigger pickle than they started in.
I've noted here on this blog before...or perhaps it was elsewhere (in the comments of a fellow blogger's blog post)...that I need not create terrible monsters or brilliant death traps to cause harm to the PCs created by this gaming group. All I need to do is place a cup of coffee on the floor in the middle of a room and within a hour they will be trying to kill each other or destroy the building that has the room in it in order to save the world from what they are certain is a deadly menace beyond all reason. It is instead, quite simply, a cup of coffee in a room.
So you can keep your dragons and spring loaded floor panels, your pits of acid and well-organized goblins. I can TPK four seasoned veterans of gaming with a hot cup of java.
This is the face of evil.