Please do me a favor~

He is a tall person, 2 meters high, and as a result he has to lower his head when he enters the classroom to avoid being attacked by the door frame.

It made us mistakenly imagine that he was bowing before he came in. Wasn't it over mind the manners? It was extremely strange. Every time he talked with the Chinese students he would have a poker face; no laughter, even when we were talking about something funny. It seemed as if he didn’t like playing jokes, however, he would then burst into laughter when we discussed something boring.

Sometimes he screams with laughter and leans back in his chair, almost making it fall backwards. His Adam’s apple dancing in his neck while his full beard is jumping.

We Chinese students sometimes look at each other in speechless confusion, thinking about whether the teacher is out of his mind.

I wasn't clear on the text in blue, so I left it as is. 

I loved the story, however. You have a good imagination and this is conveyed through the descriptive skills within your writing. I partcularly enjoyed the image you created with the teaching bowing at the classroom door, and I could visualise his Adam's apple doing a strange dance underneath his beard. Very well done. I would like to read more of your stories.