Are You Teaching?

One day, James went to China. He didn’t know the location of the school, so he asks the chinesse man.
“Good morning sir, do you know the school location?” Ask James
“Yes I do. Just straight ahead and turn left.” Answer the chinesse man
“Thank you sir.”
James walked far enough and finally he stops in front of the school yard. He didn’t know anybody there, because he was new in China. So he asked to the other chinesse man.
“Good afternoon sir. Are you teaching here?” Ask James
“Yes sir, I’m teaching.” Answer the chinesse man
“So it means that you are a teacher, right?”
“No sir, I’m not a teacher.”
“But you are teaching here, right?”
“Yes sir, I’m teaching. But I’m not a teacher.”
“But you are teaching here, right?!” Ask James badly
“Yes sir, my name is Tea - Ching. My father is ching, and my mom is Wu - Ching” Answer the chinesse man.