I had a parent of one of my Pre-K 4 students tell me this morning that they went to a Chinese restaurant over the weekend. It turns out his son said "xie xie" (謝謝, or thank you) to all the staff at the restaurant! The dad said that he didn't know what his son was saying at the time, but the staff of the restaurant understood the boy and what he was saying--and replied appropriately, with "bu ke qi" (不客氣, or you're welcome)!
It's so nice to know that what you're teaching actually gets through (on occasion)! ;-)