I got to see an exhibit of "The First Emperor" when it was in London a few years ago. They are impressive enough on tv, but, in person they are far more so.
After seeing the exhibit, my son and I read everything we could about it the army. We were most fascinated by what the river of mercury would look like... but, all of it sounded pretty darned impressive. Good fun.
By chance, the following school year, his class did a unit on china and his big project was about the terra cotta army. That was back in 1st grade, but, I know I've still got it around here somewhere.