Recent discussions around school lunch portions in the staff room generated a lot of ideas; however, it was just by random luck that an answer popped up. A few of us who work at multiple schools have been perplexed by the fact that sometimes we are given portions like someone at Rajneeshpuram would expect and other days we receive enough for a family of four and still there are leftovers.
My first guess was that they have troubles estimating portions for the office because people go off on business or are absent for other reasons, but that variance would seem to affect all of the schools equally.
On Monday the lady responsible for serving our lunches was trying to pawn off extra Okara Croquettes and having trouble getting takers. When I commented on the overwhelming quantity of food, her response fired a lot of synapses in my brain and I came to the answer. Mind you, the synapses were firing slowly and it took awhile to put two and two together.
Extra food and utensils are delivered to the office because any class with a shortage must send representatives to the office to retrieve a supplement (after being forced to explain in detail why they need it.) When a few classes have low attendance because of flu, there is very little need for the office over-supply. Naturally the 400+ student schools need a larger overage in the office for contingencies than the 100 student schools, so they have a greater chance of large portions.