Did you report the loss to your school, and/or the police?
And do you have the serial numbers of both devices? Sales receipts and their boxes might have the items.
Matching the handwriting yourself would prove nothing and do nothing. Even if the police did it, they wouldn't be able to prove who took it from that kind of statement. And, sorry to dash your hopes, but the police will probably not be able to do much about it except record the statistics and be able to notify you if they ever do seize it from someplace else - if you have the serial numbers. (Like pawnshops, etc.)
You could check pawnshops in the area to see if both pieces of equipment turn up. Do NOT say you're looking for your stuff. Let's say you find BOTH items in one shop. Do NOT tell the shop owner. Leave and then call the police - but have already reported the theft and have the serial numbers when you make your first police report, or you'll get nowhere. And keep in mind that pawnshop owners may not have the items on display for a little while (if they've been "pawned" instead of "sold" to the shop.) The odds of recovering that way are very small.
I'm afraid you're probably boned. I lost a pocket computer once that way back in the 80s. And that was when they were *expensive*. Never did get it back. It taught me some valuable lessons that you probably now know:
Now you know that in the future you need to protect bags at all times in public that have valuable items in it, take down serial numbers of your things, and maybe not carry valuable things to school with you that you don't have to have.
Good luck! I hope you find them.