American-born Chinese, the graphic novel by Gene Luen Yang might be an excellent starting point for discussion, especially among the older students.
You might want to frame this in a media studies, social studies/cultural studies sort of context if appropriate. PBS did a Frontline show called the Merchants of Cool that might be useful.
Since these kids are tweens it might help to focus on tween pop culture. I’ve put some links below that might help as starting places.
http://www. americaslibrary .gov/cgi-bin/ page .cgi/jp
America at Play features some American Sports and Celebrations
http://www. sky-net-eye .com/eng/dictionary/english/idioms/american
A dictionary of American Idiomatic Expressions
http://www. npr .org/templates/story/ story .php?storyId=17914370
In character, American Characters
http://www. englishdaily626 .com/ idioms .php
American Idioms
http://www. learnenglishfeelgood .com/americanidioms/
More idioms
http:// idioms.thefreedictionary .com/American
Even more!
http://www. slangcity .com/
slangs
http://www. wsu .edu/~amerstu/pop/
American Popular Culture Analysis
http:// parenting.ivillage .com/tweens/twculture/topics/0,,4rxg, 00 .html
This has information about Tween Movies and other things
http://www. washingtonpost .com/wp-dyn/content/article/2006/05/22/ AR2006052201903 .html
Tween Pop Culture
http:// tweenscene.wordpress .com/2007/03/28/what-is-a-tween/
Tween girls in pop culture
http://www. americanpopcultureencyclopedia .com/
Encyclopedia of American Pop Culture