To be honest I have a horrible memory and have been out of elementary school for so loooong! I kid- I am 30 years old but it does seem like forever ago and now have children in Jr. High. Lets see if I think back on just growing up in the U.S and what I can actually remember about what was taught about the first Thanksgiving.
From the little bit I can remember (and to be honest some quick internet research to refresh my memory) the first Thanksgiving was a gathering of the Native Americans and Pilgrims to share a bountiful harvest. The pilgrims who settled at Plymouth Rock the year prior had a hard time with their crops and lives were lost. The Native Americans helped the pilgrims with their crops; this was thought to be the reason they survived. Due to this they had a feast to celebrate their bountiful harvest.
I do not remember specifically but since I have children who have recently completed elementary school I will guess that we colored, drew or assembled a Turkey, Native American, Pilgrim, the Mayflower, and the food scenes.
That would be pretty interesting if your kids have been taught the same way or totally different now that time has changed. Thinking back on elementary school it is hard to remember but I specifically remember the picture book and all of the art stuff we would do.