This just plain stupid. IT IS JUST THE COST PER STUDENT. This is simply, the wages of all your teachers divided by the number of all your students. You need to take some courses in statistics. It doesn't matter what course you take.
What don't you understand a teacher is a teacher and it doesn't matter what course they teach. A student is a student and it dosn't matter what level they are at. The dollars paid don't care what you teach or what class you attend.
THE FORMULA IS USED IN EVERY SINGLE SCHOOL DISTRICT. If you feel there is a problem with the figure contact Education.com.