I saw a few of these around a couple of years ago on pinterest, but could not figure out how to get one, so I made my own. Poster is made for a 24x36 size. Squares are large enough for a post-it note to fit.
Each student is assigned a number and I keep a grade sheet that is numbered. As they leave the room they place their post-it on their number. I asked them simple clarifying things or anything that can be put down in a few words. It takes seconds to see who did not turn it in, and not much longer to read through to see who needs support.
Make sure to have them put their names on the post-it just in case.
You will receive one png file. I loaded mine to vista print.