Summary of The Empty School

It’s about a girl who tells us what happened one day at her school. She hanged out with her gang when one of her friends wanted to go back to school because he had forgotten his jacket. He came back without his jacket. 
The girl who is telling us the story and her friend asked why. He said that the school was empty, so they went there to check if he was telling the truth. They were suprised when he was.
They looked around and checked every single corner of the school but they couldn’t find anyone. They thought it was scary.