I do this in my classroom too. The kids put it on their desk when they leave which lets me know who is gone and only let's one girl/boy out at a time. When they return they are reminded to use the sanitizer. The kids love it so have plenty of sanitizer on hand.
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Bathroom Passes Bottle of hand sanitizer so you know they have clean hands after using the bathroom. And don’t forget to tie a rubber band around the neck so you get child-sized squirts every time.. 25 Clever Classroom Tips For Elementary School Teachers