There are some consulates who don't take this very seriously at all.

Expect questions like

1. Why do you want to go to Korea?
2. Have you ever had a criminal record?
3. Have you ever done drugs?
4. What is your degree in? Why did you get that degree?
5. How do you think you will be a good teacher?
6. What is your teaching philosophy?

It approximately takes 10~15mins. The consulate is usually laid back about the interview and will be brief so go into the interview with a comfortable mindset.