Teacher Grading Stickers - Pencil Only Lined Paper

It truly annoys me as a math teacher when my students use pen to do their work. When I'm grading their work, I can't let them get away with it, so I write notes to remind them to use pencil (and to remind their parents to buy them more pencils, because clearly they ran out). I notice though, that writing these quick little notes can really draw out my grading time. Then I thought, "If I had a sticker, I wouldn't have to write the note at all". I'm sure there are other teachers who have thought about this too. To satisfy that need, I've created grading stickers that actually help you relay important messages to several students when grading their work. It helps you and them.