I am always polite to them, after all, who keeps that school clean? And yes, I did ask them, but they didn't know anything. I know it was stolen, there's no way a cleaning lady would throw away something by mistake but still managing to write thanks on the paper, right?
A classmate just gave me a pencil that looks exactly the same, and I love it. I will still take back that one if I ever find it, though.
Stalk every possible suspect. Bring a camera. Use friends as decoys to distract them so you can look the targets over. Randomly ask people to borrow pencils or to draw you stuff (in front of you). Or use a sign up sheet of some sort to get people writing. Watch people during class.
Recruit spies. Send them out in pairs to do the same.
Suspect everyone. Even faculty and lunch ladies.
Trust no one, not even yourself. There are obviously forces aligned against you.
When I lost my pet chicken, I made a poster with "REWARD: Lost Chicken" and drew her picture on it. Someone on campus did the same thing when their bra went missing from the laundry room. You could try that, a poster would certainly catch people's eye and it just might work.
Even if it has sentimental value to you, it would probably be best to just move on. If anything, you could find a pack of them online. But if you have memories related to the pencil, you don't need the physical pencil to remember them
Just yesterday someone kicked in the back door to the house I'm closing on next week and took copper and the washer/dryer from the basement. They also kicked in the door to the garage and took the ladder I just bought 3 weeks ago (as well as some tools I used to make repairs to satisfy the bank). I'm not bothered by it because these things aren't worth getting bothered about. Insurance will handle the repairs/replacement and the things that won't be replaced (like the ladder and tools) aren't worth the physical toll of carrying the anger and the stress around.
Just move on. There really isn't much you can do about it.
I understand your point. I know it's a small, meaningless object. I don't care about its price. I have had that pencil for at least 4 years, and I have become emotionally attached to it. That's why I want it back.
Otherwise, I've lost many pencils and didn't do anything but shrug when I noticed.
I'd call the police and file a report. And then see if you can also run a story in the newspaper and on the tv. Then get a big group together and hold a rally to get your pencil back. Then I'd start gathering people up and waterboarding them for information about your pencil, and when they refuse get them to admit they were part of the conspiracy to steal it anyway and then take them in front of the school and publicly burn them at the stake.