Take a yellow highlighter (yes, any old yellow highlighter will do)
On each of your "Originals"--the papers in your file that you use to make copies-- make a notation. I write "O" for "Original", but you could write anything, really!
It's a bit hard to see, but can you tell that I have a faint yellow "O" at the bottom of this paper?
When I make copies, the yellow doesn't show up, so it becomes a clear copy for my little friends.
This way, I'm never confused about which is the original. It helps to prevent me from having three "originals" that make their way into my file.
Do you have any SUPER SIMPLE tips that have changed your teaching life?