[kohyoongliat]

Could someone please edit this passage for me? Thank you very much.

It was April Fool’s Day. All my classmates were very happy. A few of suggested playing a prank on our form teacher, Mr Tan.
Gabriel, the leader of the group, switched Mr Tan’s chair with a wobbly one. After that we went back to our seats and sat down and waited for Mr Tan. Before long he stepped into the classroom, As soon as he sat down on the chair, it gave way and he fell down with a loud thud. When we saw that, most of my classmates were laughing.
Soon we realised that Mr Tan was unconscious. The monitor quickly rushed to the principal’s office and informed the principal about Mr Tan’s condition. She quickly phoned the ambulance. About twenty minutes later, an ambulance rushed Mr Tan to hospital. An X-ray showed that Mr Tan had broken his spine.
The principal was so furious on hearing the sad news that she ordered that Gabriel be caned in public. From then on, Gabriel stopped playing pranks on anybody.
We were very sad when we learned that Mr Tan has to move around in a wheelchair. Most of us cried on hearing the news because he will not be able to teach us any more and because he was our favourite teacher.