English can be very confusing at times. Let me share a conversation between my two native colleagues tonight.
A: I am going to have a final exam today.
B: Good for you. Is that the first class or the last class.
A: Uh...It's the final exam, not the first class.
B: Yeah, I mean is it on the first or the last class.
A: Hmm...It's the final exam, so there will be one more class after the test.
B: Yes, I know that. You teach two classes tonight, right? Is it the first or second one?
A: Oh...it's the second one. (He finally got it!)
Note:
1. We teach two classes in the evening.
2. There is another class after final exam.
3. The last class can indicate either the last class in the whole course or today.
4. The course ends with one more class after the final exam.
