Kidshealth.org has some good materials exploring sportsmanship ideas with different age youth. Start with a discussion such as:
Describe what it means to be a good sport.

1. What behaviors demonstrate good sportsmanship? What behaviors don’t?
2. How do kids learn sportsmanship? Who or what affects this the most? Why?
3. Why is it important to be a good sport? How does good sportsmanship affect the way you feel while playing a game?
4. How does unsportsmanlike behavior affect how you feel and play?

Follow-up with one of the age-appropriate activities found here: http://kidshealth.org/classroom/
Activities include such things as deciding if a player in the case example is behaving as a good sport or not, make a skit about sportsmanship, etc.

Source: Kidshealth.org

CRE Calendar Usage: 2nd Edition