Your tax dollars are going to the ever-increasing costs of building maintenance, utilities, staff salaries and benefits, transportation (busses), computers, books, desks, blackboards, etc...
And, with the current economy, the school boards are even being asked to cut their budgets further. There are a lot of teachers being laid off and furloughed right now as part of budget cuts.
I remember we had to provide our own school supplies even when I was in grade school (30 years ago). But, at that time, the list was very basic (crayons, pencils, scissors, glue, pencil box). Personally, I don't mind sending in some supplies to help the teachers out so it doesn't come out of their pockets. But I think that some schools with more outrageous lists should sit down and rethink what is really "necessary".
