Race, Ethnicity, and Nationality are explained in the following video.
Elaine's boss does not want to shake hands with the Japanese business men because he just sneezed and coughed. However, he does not consider his language choice when explaining why.
Ross wants his son to learn about part of their Jewish heritage and Hanukkah traditions.
You can see the difference between high and low context cultures by how each child writes the instructions for this simple task.
We can see this illustrated in the following clip when Rachel accidentally teaches Ben profanity.
In the following clip, Sheldon does not understand the pragmatic rule implied in Raj's question.