I hang these above three folder pockets I post on the wall. Instead of giving students an exit ticket (let's be honest, they either end up on the floor, scattered across my desk, or in the trash anyway) I have students write their name on an index card or slip of paper and put it in a folder on their way out.
This made my life easier because...
*I no longer have to make a closure activity for each lesson
*It's MUCH faster and easier to get a glimpse of which students need extra support and which are ready to move on
*I don't have to worry about "running out of time" for a closure activity
*It's perfect for those lovely "unannounced" observations
**You can also post these on your door, a bulletin board, or above bins/trays.