The white board

There was once a teacher name Mr. Yusof. He was a very strict teacher. He had exactly 20 students in his class.  Whenever he gives his students any homework, his students would have to inform him if he or she was finished doing the homework. One day, he gave his students no homework. But, at night, his phone rang. He picked up the phone and ask “Who is this?” “Hello teacher, I am student number 21.” Said the person on the other side. “What? But I have exactly 20 students in my class!” Said Mr. Yusof. Before Mr. Yusof could say another word, the person on the other side had hung up.

The next day, Mr. Yusof asked the class “Who called me in the middle of the night?!” He said with a deep voice. Since that nobody called him, nobody answered him. Mr. Yusof punished the whole class. On the very same day, in the night, the same person called again. And said the same thing. It happened for weeks until one day…

“Hello teacher, I’m student number 21.” Said the person on the other side. “Okay just who are you?!” Asked Mr. Yusof in a frustrated voice. “I’m the student that you had never paid attention too.” Said the person on the other side.

The next day, Mr. Yusof moved to another school and never came back. On that very same day, two men came to change the white board. When they took the white board of the wall, they saw that behind the white board, was a dead girl holding a phone in her hand.