Summarize the following:
Ask your child's school for information on any community programs that are distributing free school supplies. Typically this is requires a family to already be identified as low-income. However, even if you do not qualify for some reason, school staff may be able to point you to resources for the community in general. Teachers are usually aware that for some families, school supplies are a real financial hardship. He or she can often help you out--but only if you speak up.  For example, faculty in schools often have "lost and found" items put aside from last year for those in need. Or even donations from different organizations. Teachers will often have an extra supply of items for students. A savvy middle school math teacher will have multiple calculators squirreled away for kids who do not have access to one. Many teachers in the United States pay for school supplies from their own pockets, often because they know some families simply cannot afford to. These organizations collect overstocked donations from businesses and redistribute them to nonprofit organizations, like schools.
Inquire about help with school supplies if you're low income. Try talking to the teacher. Talk to your school principal about the school joining the National Association for the Exchange of Industrial Resources (USA) or a similar organization in your country.