Donate and recycle
The school year has wrapped up and you have leftover supplies. What can you do? As of yesterday, SCARCE, the wonderful environmental education organization, began accepting many materials for reuse through their tools-for-schools program. In addition to educational supplies, SCARCE recycles many other items. Check their acceptable items list and procedures here.
If SCARCE can't take certain materials, search for other options. Spend some time exploring their website; this organization provides many resources and services, including a calendar of recycling and shredding events.