My wife was a substitute teacher, and all they asked her for was a pay stub that showed the school district name on it. I would think that should work for you as well.
My wife is a secretary is our school district and we received the discounts. We just had to show her ID Card . They didn't ask for it but we had a copy of her pay stub which states on it the school where she works.
Just came to agree. When I used this I was a sub and just showed my paycheck stub. I don't even remember if they asked for it, but I would have it just in case.