Over the years I have found that students like to abuse the privileged of having a bathroom pass available in the classroom. Amazingly they need to magically use the bathroom once work time begins. I wanted to create a way to monitor and reduce bathroom usage in the classroom. I created a two pass system. The students are allowed to use one pass in the morning and one pass in the afternoon. These passes do not include any "class bathroom breaks." Let me describe the system I have in place.
Here is what it looks like...
The students have to "check out" when they need to use one of their passes. The "morning pass" is a bathroom pass used before lunch. The "afternoon pass" is a bathroom pass used after lunch.
The students will choose the proper stick and place it behind their cards on my behavior management "card moving" system. Yes... I have it pulling double duty. Not only can the students monitor their consequences, they can monitor how many times they are using the bathroom.

From this picture you can see that Lana has used her morning pass and Jibril has used both his morning and afternoon pass (Jibril has used all his passes for the day). Once the students place the proper stick behind their name, they must then place the "boy's pass" or "girl's pass" on their desk. This allows me to see who is in the bathroom and keeps them from taking the pass into the germ infestation we call the bathroom. This system has really worked out well over the years and really helps minimize extra bathroom visits. Students do understand that if they have an "emergency" they may go even if they have used their passes. But just asking the simple question "can you wait five minutes?" will reveal if the students is truly having an "emergency" or not.