Teacher Trap

The head teacher came into our class and told all of us that our teacher was sick.
"Therefore, I am going to choose a student to teach the class,today"
To my surprise he chose me!
So,I went up to the white board and I going to teach all of them. And everyone is very noisy so, I cannot teach them.However I asked them to quiet and write the lesson.And then I explained it slowly and clearly. But every always say "they cannot understand and they want their teacher back",and they called me "The silly teacher".I was so angry but suddenly I had one idea.First, I said that "Everyone if you want your teacher back please quiet and listen to me, your teacher will come soon ". But it just my trap. Everyone was very quiet and really pay attention to me.
Finally, when I get out of the class the head teacher told me that it is good trap.