This is something that I started doing last year and not only did it work well for me, my principal LOVED it! :) I simply typed in the student's name and allergies (there are so many these days) printed it out, and put it on the door where any teacher, or substitute could easily identify which students had allergies. This definitely came in handy when it came time for snacks, treats, holidays, birthday parties, etc. I thought it was very useful last year and I plan on doing this every year! Its so simple, yet so useful.