The 9/11 Memorial Foundation has created an interactive website called Lady Liberty.
After 9/11, someone placed a replica (not full-sized, of course) of the Statue of Liberty outside a New York City firehouse, and people began attaching messages, photos, and art to it. At the website, you can explore the messages. A teacher’s guide is also available for free.
I’m adding the link to The Best Sites To Help Teach About 9/11.