Sorry you are going thru this ! Great suggestions in the above posts, and I might add a few that worked for me, and work for my clients:

1. Count backwards from 1000 by 7's
2. Silently sing a song, something like the children's song B-I-N-G-O and each time u sing it, leave off the last word.(or letter in the first few rounds).
4. Learn diaphragmatic breathing - its the way a newborn baby breathes - all that moves is your belly. That is the way we should alway breathe - but when anxious - we tend to go into upper chest breathing. When u start to feel anxious (from your post stating u use a paperbag I take it this is a major issue for you) - put a hand on your belly and focus on making your belly go IN when exhale, and OUT when u inhale. Practice this laying down until you learn how to do it - sometimes if u have been chest breathing , you might feel a bit dizzy at first because your system is not used to getting the oxygen this will give you.

As for "escaping", unless they have bars or locks on the door of your classroom - you actually CAN escape from the classroom. If we can use rational self statements such as "I know if I feel anxious I want to leave the area, and the door is not locked, so I could leave if I choose too". (However - in all honesty - anxiety attacks/panic attacks are within us - NOT in the area we are in, the room we are in, etc. By thinking we need to FLEE - that makes the fight or flight response kick in, making the anxiety worse.). If you can really work on the thoughts you have about "escaping", you will feel less need too. (I used to RUN - and I mean RUN when I had attacks, but when I realized I could not outrun my brain, I realized I could talk myself thru the attack).

Great books recommended above, but I strongly recommend "Anxiety, Phobias and Panic - Taking Charge and Conquering Fear" by Reneau Z. Peurifoy. NOT an easy reading book - but a step by step guideline to deal with these issues. I used this book as a guideline for 7 years in a Support Group I facilitated........it was MY anxiety "bible". One of the best out there IMHO !

ALso , write some soothing statements on 3x5 cards. These can be about your pet at home, your family, a favorite vacation spot, your best friend, a childhood toy, etc etc etc. Read those to "trip your thinking away from the anxiety".

Good luck ! There IS life after panic/anxiety attacks!!