I'm a first year teacher and I recently had an issue where a student or students plugged in 2 hot glue guns, set them on top of a wooden cabinet, and walked away. I was unaware of this until I came back after lunch and smelled something hot. My construction class of 23, the only class in the shop that morning, will not confess to who did it. I called the students out of lunch and their homerooms to come down and talk about it. The older students, who were in lunch at the time, refused to come down and talk to me until they were called out a second time. I have decided that they will no longer have shop privileges until someone steps forward and we have gone over shop safety again. I have administrative support for this. The students will be required to get 100% on a safety test before they are going to be allowed to begin working in the shop again. I feel that this at least partially happened because I have a different teaching style and attitude than the teacher before me and the students don't like it. I tried being a little more lax with this class and get them out in the shop more often because a lot of them are hands-on types, who originally thought it would be a blow off class and they could do whatever they wanted. When this happened, we were working on cleaning up from our weekend festival and organizing all the stuff sitting around the shop so we could start working on a simple project when we were finished with talking about lumber. The students were quick to blame one person for it happening, and he was called to the office and talked to. He swears it wasn't him who did it and no one else has come forward.
What are some activities and stuff that I can do with these students in the classroom to help them fully understand the severity of what happened and prevent further issues?