During night self-study hour

Although most Korean high school students have to stay at school until 10,
they still can enjoy their school lives with their friends.
Since they spend most time of a day with their classmates,
they can form a good friendship.
This video clips are filmed by 3 typical Korean students who lipsync
during night self-study time called "Ya-ja."
Teachers monitor students studying on the hall way.
You can see that the three boys keep watching if the teachers come.