Have you ever been at your teacher table deep in to teaching your kids how to blend, then you look up and you notice little Johnny isn't sitting at his desk? I've placed an "Exit Station" in my class to help me know exactly where my students are at when I look up from teacher table.
I've used blue painting tape to divide a dry erase board. I've labeled the dry erase board with the possible places they could be at without asking for permission. Students will sign their name on the board when they leave and erase it when they return. This will allow be to be able to glance at it from my teacher table across the room and know who not in class at that moment AND know exactly where they are at.
I've also placed two handsantizers, one for boys and one for girls, that the kids will place on their desks when they go to the restroom. When kids sign out to go down to the bathroom they place the handsanitzer bottle on their desk. The purpose is three fold - I despise bathroom passes that travel to the bathroom because who knows what happens to them when they are there, I can look up and know why the desk is empty, and kids will sanitize their hands when they return to class.