Not baby related, but...

Not baby related, but wanted opinions. So my oldest son just started 4th grade & they sent home a list of supplies to buy. We bought everything on the list, & I had him put all of it in his backpack. I noticed that most of it kept sitting in there, so I told him to ask his teacher if this stuff was meant to stay at home or at school. Well today he comes home & tells us that when he asked, she said, "Well how about we give some of this to other kids in the class that need supplies" & then gave a bunch of it to other kids! Am I wrong to be upset by this?? Not that I don't want to help out a kid in need, but this is stuff they told me that MY son needed & then she proceeds to just give it away without consulting me! School supplies aren't cheap & we live somewhat comfortably but aren't super well off. Opinions??