In those schools were always a teacher wonder about the Korean students who are reluctant, hesitating or even lingering to answer his questions, no matter how simple the questions are. Here's my thought that could be one of many reasons.
In the first, we are inclined to think again and again before uttering something. Not only about someones' question or asking but also what is in your mind, even though you have the obvious answer or you know for sure what you are trying to say. We believe the words that come out of your mouth can be used in deciding what kind of person you are and it may be too late to regret once the words that you shouldn't have said are sprung out because you cannot retrieve those words.
Secondly, we are not familiar with being in the centre of other people's gaze. Not to mention that attracting public eyes makes us feel very uncomfortable, there is other reason of it. People in my country, where Modest is regarded as No.1 behaviour, tend to consider it as an airing or bragging to answer a question that other group members may not know. In many times, it makes us suppress the enjoy of boasting.
Finally and most importantly, we don't like being shamed. It doesn't matter how much you effort to persuade us or insist on that there is no reason at all for feeling shamed at throwing wrong answer. We just dislike it.
