Last year I had a classroom and a separate cubicle in a shared office. The students had access to the classroom during required evening study from 7 to 9 every night, during which time they were unsupervised. This was how every classroom smartboard had malware and viruses.
Last year I had students go through my things during periods when they knew I would not be at my desk. My Chinese colleagues working at neighboring desks watched it happen and told me about it when I returned, but made no effort to stop it. In fact, they told me that it was my fault for not locking up everything at my desk before walking away from it. (Note: they do not do that themselves.)
This year we are in temporary space while our building gets remodeled. Now my desk is in my classroom. This means that students will be able to go through my things during evening study.
I have a rolling filing cabinet with a lock, but that lock has been broken since before I began working here. I have a bookshelf with a locking door, but no one knows where the keys are. The locks of these items are the type that can stop someone opening them swiftly, but they will be no challenge for students with two hours of unsupervised time with them.