The depth of our discussion about culture depends on the topic and the interest of the English language learner. I'm often able to explain the origin of many aspects of "American culture," the "why" of what we do, and a bit of history about the custom. To further our conversation practice, I also elicit information about the customs in the student's home culture.
Last week, a student stumped me by asking me the "why" of something we Americans do. She wanted to know why we often ask when receiving a present, "Should I open it now?" First, I was able to confirm that, yes, we usually do ask this question. However, the "why" of it was something I couldn't definitively answer. I speculated that it has something to do with economics and embarrassment. That the receiver of a gift doesn't want the giver to feel embarrassed about the cost of the gift, whether it is a costly or an inexpensive gift.
I'd love to hear some suggestions from other people familiar with American culture as to why we ask, "Should I open it now or later?" And I also welcome non-Americans to share their customs around receiving gifts in their home countries.