notepad and pencil for each patrol.
instruction sheet for each 'spy' volunteer.

Arrange for two volunteers to be stalked by each patrol.
Prepare a list of instructions for each spy pair to perform. Such as, [Do 10 jumping jacks in an open field] or [Arrange 30 rocks in a circle].

Enemy spies are suspected in the area. They may try to communicate with other spies by leaving clues or doing strange behaviors that other spies will understand. Your job is to secretly follow and monitor a suspected team of spies. Report back everything that may help the Central Defense.

Instruct each spy team that they will head off from the starting point in a different direction than the other spies. They should do the tasks about every 3-5 minutes as they hike across the camp and back. They should also occasionally stop, hold their head up high, and slowly look around as if they heard a noise or are suspicious of something. (This should give following scouts a chance to hide, especiallly if younger.)

Patrol leaders are each given a notepad and paper. They are to record any strange behavior observed.
Each patrol leader reaches into a hat and pulls out the name of a spy team to stalk. They will silently stalk that team, recording what they see and trying not to be seen.

When everyone has returned to the starting point, the stalkers show their records to the spies to determine how many behaviors were correctly noted.
Spies take away points for each person they noticed following them.