The sentence you provided seems incomplete, as it ends with "their." It's likely that you intended to complete the thought with a noun or a pronoun. Depending on what you want to convey, here are a few possible completions:

1. American teens are setting an example for their peers.
2. American teens are setting an example for their community.
3. American teens are setting an example for their generation.

If you provide more context or specify what you want to say, I can help refine the sentence further!