Here's one more suggestion, take it for what's its worth :)

At my daughters school I did a "letterboxing" hunt for Valentines day. I hid
6 boxes and then split the kids up into 4 groups. This kept group sizes down
to a minimum. I started each group off at a different box with the same
order. This kept the "stamping in" time to a minimum so they were less
likely to get bored waiting for their turn. Instead of having them each make
their own stamps I let them each carry a washable marker of their choice and
use their thumbprint. It was quick and easy. They each got to stamp the box
stamp in their "book" they'd made. They loved solving the "clues", loved
stamping in, and loved taking their book home with them. After the party I
tossed all the log books from the boxes and rehid them out in the public as
regular letterboxes. All boxes for the party were hid in the school or on
the playground.

Maiden


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