What is "caucasian"?

The journal topic for the day in Geography was, "What is Caucasian?"
My students normally come in, write down the topic, and then write for 5 minutes. It takes this small group of ESL and LD 7th & 8th graders about 5-6 minutes to write the question and 3 complete sentences in response.
This day, they wrote down the question, then -
"Miss, what is 'cow-cass-ee-an'?" "what mean this word?" "I think it is someone from caucasia-land!" "how you say this?" "Caucasian not in my dictionary!" (by that, Ji-Won meant that her electronic dictionary could not provide a Korean equivalent for the word)

The point was to show that there really is a group of countries called the "Caucas" countries, and it is between Russia, Turkey, and Iraq, and so "caucasian" really does not mean what most North Americans think it means.
Unfortunately, my kids had no idea what it means, so my genius idea to have students write about what they assumed the word meant backfired.

*sigh*
Teaching is all about thinking on my feet. Even if my kids don't know what that word means, either.

I offered to give them a hint. They love hints. "Drew, Brianna, and I are all Caucasian," I said, pointing out the two missionary kids whose parents are from the U.S. and including myself in the group so that they wouldn't feel picked on. "Monica might be Caucasian, but there's still debate on that" I was afraid Monica, the only fully ethnic Mexican in the class, would dislike being pointed out, but she beamed proudly. She liked being a little mysterious, it seemed.

"Yellow-hair!" one korean shouted out. I reminded them that drew & I are both brunettes, and that there was no debate about Monica's decidedly non-yellow hair.
"yellow hair & blue eyes - what is the word for that?"
A furious korean conversation - with enough English and Spanish words sprinkled in for me to get the gist of the conversation - followed, and they decided that 'blonde' was not what caucasian meant or they would have heard of it before.
Sandy, the one who had looked up 'caucasian' in her dictionary, started demanding a translation for a korean word. No one knew what that word would be in English, so they thought it could mean caucasian, except that since cuacasian wasn't in her dictionary, it may not have a direct Korean translation anyway.
"westerner!" she shouted, proud of her quick work at the electronic dictionary.
"American!" shouted another student with even less grasp of the English language but also without a fancy electronic dictionary.

I smiled to myself as they started to understand the concept, but I still wanted them to write. I told them to write down their best guesses and then we'd talk about it.

When I explained that "caucasian" was a word used in the U.S. to talk about someone with European heritage, they looked confused. Drew was especially confused bc his family was from Tennessee, not Europe. (no joke) Finally, I said it was a polite way of saying "white people" kind of like "african american" is a nice way of saying "black people".

They wanted to know what is the nice way of saying "asian people". I said "asian people" was a nice way of saying it. But they weren't buying it - why didn't they get a special word like caucasian? Especially since caucasia-land is an actual place, and I wasn't from there but I still got to check off the caucasian box on my census form?