"The Story of an Hour" is good to use in teaching irony. Another of Chopin's stories, "Desiree's Baby," would work well also. You might also look at "Lamb to the Slaughter" and "The Necklace."
Have you considered 'The Story of an Hour' or any other short stories by Kate Chopin? I also liked 'The Lottery' because it shows how traditions lose their meaning. Both stories require deeper thinking. Maupassant's 'The Necklace' is another good one that might resonate with young people when compared to the meaningless acquisition of things today--and what it has cost so many to live in such outlandish luxury. Just a thought.
E-notes has notes on some of these.
How about looking to other genres? A lot of kids in that age group are reading the Ember, Harry Potter, and Twilight books, so a science fiction story like Tom Godwin's "The Cold Equations" might be a good choice.
Not a short story, perhaps, although "The Dragon" by Ray Bradbury is a good one I have used before. However, I have used the song lyrics from "Ironic" by Alanis Morrisette with my middle schoolers before, and they have reacted well to it.
The opening stanza goes:
An old man turned ninety-eight
I hope that helps.