Great idea! Maybe they could just turn a different color?
I’ve been creating little grading checklist for the submit bubbles. They’ve made it easier for me to remember which bubble(s) to check and what to look for. It’s also easy to give each kid their little square that shows why they rec’d the grade they did. I give them the opportunity to try again and be regraded. They just return the paper so I can see which bubbles to check and what I need to review.