Numbers, teeth and yawning

This is a review from the last year lesson, numbers in mandarin session in my class. The numbers are until 18 (shi ba).
When we start to begin counting 1 to 18, it happened that one of my students was yawning so big that the whole inside view of his mouth was seen by me. Well it's still in the morning, but I never dreamed of last night that I will see the biggest yawning today in the morning :)

"Wow Zio, you are yawning in front of everybody." He's just smiling while still yawning.
Suddenly I have an idea................................................
"And now everybody must count Zio's teeth."  I am saying it with my wicked smile. LOL :D. Because  I think this is a good idea for learning numbers.
"Count only the upside teeth." I continued. Because I was teaching them 1 to 18 only.
"Ok Zio you start yawning in count of three, 1.......2.........3........yawning........ !!! "  :)
And then everybody got closer to Zio and start to count his teeth.


" Oh Zio, you only had ten teeth on upside. And now I will open my mouth, and everybody count my upside teeth." I was asking.

After finish counting, they all said," You have 16 teeth, Mr.Danny."
"Why do you have 16 teeth, sir ?"

I answered it," Because I am already grown up, and anyway my mouth is bigger than yours." :)
"All of you will have 16+16 teeth later when you are big."

"And Zio next time, please go to sleep earlier at the night before, so you won't yawn again in the class in the morning." :)

1 = yi

2 = er

3 = san 

4 = si

5 = wu

6 = liu

7 = qi

8 = ba

9 = jiu

10 = shi

11= shi yi

12= shi er

13= shi san

14= shi si

15= shi wu

16= shi liu

17= shi qi

18= shi ba