Thanksgiving.
Sara's slideshow is more appropraite for older students (4th-6th), as it goes into some detail about the Holiday. Though it has a lot of English text, there are also a lot of pictures, and an interactive presentation is desireable. At the end are videos of the famous Macy's Day Parade.
A wordsearch includes all of the traditional Thanksgiving meals, such as gravy, turkey, and corn on the cob.
Watching A Charlie Brown Thanksgiving could also be a fun challenge. I would suggest watching it twice and then completing a questionnaire about it, or filling in the lyrics to a song.For the younger kids, fun activities include: making turkeys (they can begin by tracing their hands and using the shape of their fingers as feathers!), making other Thanksgiving Day crafts, and learning Thanksgiving songs.
For more thanksgiving activities, visit this French ESL Thanksgiving website that has many English activities about Thanksgiving, and print flashcards here.
This ESL site also has very good activities planned, including crafting and coloring a mini version of the Mayflower!
