Set up different Frisbee Golf "holes" within the playing area.
Each "hole" should include: a) a base from where players must start, b) a hoop which is the target, and c) any number of obstacles around which players must throw their frisbee on their way to getting it in the hoop.
Divide your class into small teams and provide each team with a golf scorecard (this could be a simple piece of paper). Each team will start at a different "hole".
Players take turns attempting to get the frisbee into the hoop (while respecting the obstacles).
The amount of throws it takes for a player to get their frisbee into the hoop is their score for that "hole".
Players play each of the "holes" and then add up their scores.
The goal is to get the lowest score possible.