Would you please correct my mistakes? (*:*)

While I was studying in middle school, one of my classmates was very witty person and skillful in application softwares such as the Office, the Photoshop etc. One day he brought an A4 paper that he had typed on it as the following:
“Teachers entrancing to this class is prohibited”

While I was studying in middle school, there was a classmate who was very witty as well as skillful in application softwares such as the Office, the Photoshop etc. One day, he brought a peice of A4 paper ,which he had typed on it the following: “Teachers are prohibited from entering this class".

He had designed an arm and put it under the mentioned text. While he was showing his art to us, one of the rude students, that always was sitting on the last bench, came and caught it. He pasted that paper on the door of the class in fewer than 30 seconds.

He had designed an arm and placed it under the mentioned text . While he was showing us his drawing , one of those rude students who normally sat in the back came forward and snatched it. Then, he pasted it on the door. He did all that in less than 30 seconds.

Immediately after pasting it on the door, my teacher came and saw the paper. Without wasting time, he took and showed it to the manager who was walking in the corridor.

Right after the art had been pasted on the door , my teacher arrived and saw it. Immediately , he tore it off the door and showed it to the manager who happened to be walking along a corridor nearby.

The manager came to the class and gave a chance to me and my classmates to present the person who had done such a bad behavior in less than 5 minutes. The time was passing quickly but anyone didn’t tell anything.

The manager came into our class , and gave us 5 minutes to point out the student who did the drawing : it was considered an inapproriate behaviour any students to do such a thing . The time soon passed , but no one told him anything.

Eventually the time finished and the manager sent one of the students to his office to bring his scissors. It was very difficult situation because in fewer than 30 minutes all the students would make bald by his scissors.

Soon , the time was up , and the manager then sent one of the students to his office to bring him his scissors . It was a ominious sign because he threatened that  all the students would be made bald by the scissors in 30 minutes, if the culprit was not made known to him.

Some students were frightened of results of telling the truth and the others wanted to prove their friendship to him. After finishing our time, the manager took his scissors and made all the students bald.

Some students were frightened to keep the secret any further , but there were others who wanted to show solidarity with the culprit. After the 30 minutes had passed , the manager took his scissors and balded all the students with his scissors.

It was awful and terrible; all the students from other classes were pointing us by their fingers and were laughing, when we were in the court of the school. After that I decided to tell the truth and run and never be silent when my interests are in danger. It was one of the most important lessons that life taught me.

It was an awful and terrible experience : all the students from the other classes were pointing to our bald heads laughing when we were in the school's courtyard. After this episode , I have decided to tell the truth/ to not keep silent if my interests are jeopardized/threatened. It was one of the most important lessons that life has taught me.

I have changed the essay a bit to make it more readable . Interesting story ,but a bit too long for many to correct , especially when corrections are plenty ))