This is a horrible thing...

This is a horrible thing for a teacher to say, but some kids are just dumb. Maybe this is just the cynic coming out of me, but it's true. I do try to be very patient with my students and remember the fact that the Korean educational system is very stressful with lots of extra studying and homework and tests. But the following incident which happened yesterday in my Junior 5 (high intermediate level and 12 years old) class is proof that some kids are just dumb, no matter what.
I was teaching a lesson on future questions with the word will and was going around the room asking every student a question.
Me to John: What time will you eat lunch tomorrow?
John: Blank stare at me
Me: What time will you eat lunch tomorrow?
John: Long pause. 1:30.
Me: Okay. 1:30.
Other students: 1:30? What? Really?
John: Confused look
Other students: Your school eats lunch at 1:30? Really?
John: Not 1:30.
Me: Okay. What time then?
John: Blank stare. Writes something on his book
Jake (sitting by John): 12:10.
Me: John, do you eat lunch at 12:10?
John: Shakes his head.
Me: Okay, what time do you eat lunch then?
John: Confused look
Me: John, you think about it while I ask some other students.
I ask about 3 students a question and then John shouts something out.
John: I eat lunch at 7:30.
Me: 7:30?
Other students: Lots of laughing
Me: John, I don't think so.
Jake: Teacher, John doesn't know what lunch-ee is.
Other students: Lots of laughing
Me: There is no lunch-ee. Lunch-ee is not an English word. It is lunCH.
Me: John, look up here at the board (where I write). Every day, most people first wake up, then eat breakfast, then go to school. In the middle of school they eat lunch. Then they go home and eat dinner and then go to sleep. Understand?
John: Nodding
Me: Okay, so what time do you eat lunch?
John: 5:30.
Other students: Lots of laughing. John eats lunch-ee at 5:30!
Me: No one eats lunch-ee. It is lunCH (writing lunch-ee and lunch on the board).
Jake: John eats lunch at 12:30.
Me: Okay, great. Now John, say a sentence.
John: I will eat lunch at 12:30 tomorrow.
Me: Thank you.
This whole exchange took at least 10 minutes and by the end of it I didn't know whether to laugh or hit my head on the board.