We have a 30 minute lunch period. Thirty minutes. In that thirty minute time period, I have to walk the children to and from the cafeteria and make sure they get their lunches and don't hurt each other. That takes 7-10 minutes. So now I have a 20-23 minute lunch period. Let's go with the maximum amount of time left, just to give whoever came up with the schedule the benefit of the doubt.
In twenty-three minutes, I have to use the bathroom, as this will be my first and only time to do so from 8:30 am until 2:55 pm. I'm fast. There goes another 3-5 minutes. Now I have 15-20 minutes. Again, I'll go with 20.
Twenty minutes left. Still have to make the kids' homework. That can take between 5-30 minutes, depending on if anyone's in line for the copier, if it jams, if there's paper, etc. Now we have to go with the maximum amount of time left, because if it takes 30 minutes on this hypothetical day, I'm way out of time.
OK, everything's gone perfectly, and I have 15 minutes left. Remember, I haven't even thought about eating yet. I'll still run into about 2-9 children who absolutely NEED me for something. 2-10 more minutes gone there. I'll probably have to return a phone call from someone relating to school, go to the office to check my mailbox, or send an email about a field trip. Absolutely best case scenario, the heavens are on my side... I have about 5 minutes left. Plenty of time to relax and eat! Let's hope I haven't forgotten my lunch!
Did I mention that we have a 30-minute "duty free" lunch for teachers in my district? They always did have a sense of humor.