Ideally, approach these activities from a sports angle. Offer to cover games for your school's newspaper or do the Monday morning sports recap during over the P.A. system.
If you cannot do these activities from a sports angle, however, you should still take part as able. The skills you will learn as a reporter or broadcaster can still benefit you.
You should also look for chances to call the action at youth sporting events, whether those events are through your school system or simply within the community.