Birthday party scavenger hunt??? :)?!
Answers:
http://www.birthdaypartyideas.com/html/scavenger_hunt.html
http://www.birthdaypartyideas.com/html/mall_scavenger_hunt.html
Look at these websites, they are very helpful when you plan a birthday party. Hope you have a great party!!
Personal experience
Hm....Well, maybe you can put out objects that give you hints to where another might be hidden? or you could attach a note to it with a small clue. For example, if they find a dog bone, it will give them a clue to go to your dog bed or something. Give each team a checklist of all of the items and they can check off the ones they found.
i like hayli's idea