We have the below in E level of T.O.S.S Teaching Skills and Techniques Assessment System.
When Mr. Yoichi Mukoyama made this item, I can't forget his muttering words that he added like,
Anyway, you just smile, it's just OK.
Smiling is the prerequisite of your class lesson.There's nothing more important than that.
I give advice to my university students when they are going to a school for an internship.
"You may observe a lot of class in school. I recommend you to look at the facial expression of teachers in the classroom trying to find the teachers whose smiling is really nice."
"And If you can find the one who has the best smiling in school, you should go to him/her and ask to give you some advice."
"Because the teacher definitely is the best skillful teacher among all of the school. It's no doubt"
4 weeks later, trainees come back to university. and said to me,
"Hey Mr.Tani, I tried to find some teachers who have nice smiling."
"Uh, Honestly, no one smiled."
"What? There isn't anyone?"
"No, there isn't"
It's a true story. I have several experiences I've heard this kind of reports from students.
There are no teachers who are teaching in nice smiling. That is a real figure of real schools now in Japan.