I noticed our local technical school is offering a summer camp with a Mythbusters styled theme. This would seem to be great way to teach the scientific method in a fun way. The description for the camp reads like this:

"You may have heard the warning to keep your toothbrush far away from the toilet because nasty germs could get sprayed in the air land right smack onto your oral hygenic friend. Yuck! Is that really true? Could that really happen? Campers will put myths like this one to the test using scientific inquiry and find out just how real they are. (Err, in the meantime, why don't you move that toothbrush, just to be on the safe side?)"

Also, regarding critical thinking, I've heard good things about the The Fallacy Detective, but I have no personal experience with the product. The description says it also includes "The Fallacy Detective Game."