I recommend Bill Perry’s useful little paperback “A Look Inside America: Exploring America: Exploring America’s Cultural Values and Holidays.” You can order a used copy at www.Amazon.com for pennies, plus the expedited shipping cost of $7 to guarantee that you get it by Nov 12. Otherwise pay $3 for regular shipping which guarantees delivery by Nov 24, 3 days before Thanksgiving. The book has 6 good pages on Thanksgiving, including a vocabulary list page.
I just addressed this in my latest volunteer newsletter on 10/30 at http://www.isivolunteers.org/latest-isi-info-newsletter . Blessings, Julie