Invite a child to bury the treasure. But not simple, and the treasure - message to descendants. What kid wants to inform the people of the future? Let them write or draw it on paper. Maybe he will want to send news about yourself? Help him to write or draw what he had in mind. Roll the sheet into a tube and place in a bottle with a secure cap. Now he must choose a secluded place and bury his unusual treasure.
Archaeologists of the future will marvel at finding such a message.