I would feel terrible, but I know that there are a number of organization that will provide what the children need for school. There are the Veterans organizations, such as The American Legion, The Veterans Of Foreign Wars, AmVets, Disabled American Veterans, and others that have local programs to provide these supplies free of charge. There are local food share groups that do the same, also other charitable organizations have their own programs. Just check this out in your community, I'm sure you will be surprised.
I feel bad for those parents. You know they want the best for their kids and would give them what they can, but sometimes it more important to keep the lights turned on and the rent paid. Debossman makes a good point, there are organizations out there to help out, including local ministries. Hopefully, there is family members too that can help out.
I would feel bad but if they cant afford it then its okay. But I would feel worse if a parent can afford to pay for school books but they just don't want to...