Adorable Hall/Bathroom Pass using clothespins! Always know who/how many kids are out of the room. They clip a clothespin to their shirt or collar (so it won't get germy! Could also "hall pass" and see how many are gone and who they are.
The kid puts the bottle of sanitizer on his/her desk when going to the bathroom. When the kid returns, he/she must squirt some sanitizer into his/her hands in addition to washing hands in the bathroom.