For example, when people ask "We don't have to hand in the assignment right?"

Why do some people answer "No." (They meant the assignment does not have to be handed in.)

But if so, should the answer be "Yes." (Yes, that's right, we don't need to hand in the assignment.)

You're right. There are several standard questions and forms of questioning to which we often give the opposite answer from what we should. The most common one I hear is this:

"You don't mind if we come in, do you?"
To which, most people would answer, "Sure, come on in!" (But the answer should be in the negative -- "No, I don't mind.")

There are others like this. Idioms, I suppose.

Aha! This is a cultural thing! In Japanese, for example, the answer to that question would be: Yes = we do NOT have to hand it in but No = on the contrary, we DO! Actually, I think that makes sense! If the question is negative, YES should mean the negative and NO, the affirmative!

However, here in the U.S. most people will say "No, we don't."

Sra

When someone asks "We don't have to hand in the assignment right?" it is important to understand the intent behind their question. If the person is seeking confirmation that they do not need to hand in the assignment, then the appropriate response would be "Yes." This means that the listener affirms that the assignment does not need to be submitted.

However, it is common for people to use a negative response as a confirmation, especially in informal conversations or when emphasizing a point. In this case, if someone answers "No" to the question, they are actually affirming the statement. So when someone says "No," they mean "No, we do not need to hand in the assignment."

It can be confusing because the answer doesn't directly match the question, but it is a common conversational practice. To avoid confusion, it might be clearer to respond with "No, we don't have to hand in the assignment" or "Correct, we don't need to hand it in." It's all about clarifying the intended meaning of the response to avoid any misunderstandings.