Remember the stacks you made before - A, B, & C? You should have trashed all the B things - shred or recycle what you will not use or need again.
Stack C - was your Maybe pile - Take a look through and ask:
1- Can I use this in my class? - NO? trash
2- Can I share with my class in some form? NO? trash
3- Will I use this in the next school year? still not sure? keep around a minute longer
Make a Maybe file and put it in there.
We need to look at the A pile to organize it later.
Work on your C pile and see how it goes.