Many years ago when I was a teacher, I found that manilla folders came in quite handy. Not just for files but were the perfect weight for cutting out letters for the bulletin board. I often glued outdated wallpaper samples to the folder, rolling out the bubbles and wrinkles with a wallpaper roller before cutting out letters and designs.
Folders were also handy for storing flannelgraph. (An old fashioned visual used for teaching Bible Lessons) I used packing tape to close the sides of the folder secure.
I used old folders for making signs and for making Bible verse cards. I simply designed the verse on the computer, print it out and adhere it to the old folder and cut it out to the appropriate size. (Perfect for Bible Verse presentation. Add a cardboard stand to the back and it works great! For individual verses when teaching a class, I printed the verses directly onto business card stock.)
One thing I never thought of was making greeting cards using folders. Check out The Better Mom’s blog for a great tutorial. Your kids will have fun making cards for their grandparents and friends!
http://www.thebettermom.com/2012/07/family-mega-card-tutorial/