1. Inform your supervisor or the head of the section about this matterĀ 
2. Make poster and create awareness to the students about this matter.
3.Announce the consequences of this problem in the school assembly.
Totally agreed... Since this answer is giving. advice on what to do, I'll make a conversation...
Angel - Every year, at the end of each session, each class produces 10 damaged furniture. Our school is facing a huge loss. Devil - Yes. Let's brainstorm ideas on how to stop it. We can campaign somehow. Angel - Why don't we make posters and stick them all around the school? And we can also talk to some seniors about this. Devil - Good idea! We can even have a special debate session on this. Angel - So let's make sure that our students take care of school property and no furniture is ever damaged. Devil - Yeah...