Notice

It was a typical High- School, filled with laughter, joy and entertainment. Not until one of the teachers of the school goes missing and found dead in the staff room. There was nobody there, unfortunately. No signs of life from any of the floors except the one class. The puzzle that had to be solved- the riddle that the kids had to solve all alone. The class 9W, which was notoriously infamous was a group of 30 students of 'not that bad' of a reputation.
What will the answers to these mysterious cases be when the only detectives are these few highschoolers?