It has happened to all of us at some point in our career. You start handing out worksheets and and students start working on them and then you realise that you didn't keep the hard copy. AHHHHH!!! Well here is a little tip to help you not make that mistake again. Super easy and I PROMISE it does work. All you need is a yellow highlighter and your hard copy worksheet. Write copy across your worksheet and when you copy them the next time the yellow highlighter does not show up on your copies. I do this all the time now. I have even used a yellow crayola marker when I didn't have a highlighter available.