Restroom passes, breaks, and policies for teachers is always a touchy subject. It should not be. Almost every class period is geared for a length of time that a child can wait between bathroom/restroom breaks. However, there are teachers that like to be more lenient, others stern. Some teachers don't care. The best position that teachers should take is somewhere in the middle.
First and foremost, let's state that all emergencies should be handled directly. Let a student go. All teachers should be able to recognize a real emergency, and even if the student is faking, best to err on the side of caution. Of course at higher grades, the abuse factor is there. If the students know you are fair and firm, you will have no abuses to worry about. In fact, that's the key to a good bathroom pass policy.
If a teacher does not make it an issue, the bathroom issue will never be a problem. If your students see you as fair and admirable teacher, you will have no problems. The problems are mainly caused by students wanting to press your buttons. If you have built a relationship with your students, this melts away. In fact, it melts away a lot of discipline problems. Bathroom pass abuse is a discipline problem.
For teachers that would rather have tips on bathroom use, here we go.
Never let more than one student out of the room at a time. If it's a young grade, like first grade, you may make an exception.
Let's stop here. Most of the bathroom pass tips here are for older students, say 3rd grade on up. You will have to recognize the need for younger student not being able to hold it. Stress going during lunch and recess. Remind them to go as they walk out the door.
Put a time limit on it. Just pick a time 3-4 minutes is fine. No exceptions.
Nobody can ask for a bathroom pass during the first 20 minutes of class. Guess what? This tells the students you will let them go, so no confrontations. It also means that virtually all students can make it way past 20 minutes, so...? The number of students asking will be rare.
If you make it an issue and take a "no bathroom" attitude, your students will fight it.
If you are in the middle of a lesson,say,"No, but ask me in 5 minutes." Most of the time they will forget. If it's real, they'll remember.
You may allow each student one bathroom pass a quarter. That way, they know they can go if they really need to.
Always keep track of students who are gone. If something happens, you need to know where students are and who is missing.
You can also choose days. No bathroom passes on Mondays or Fridays.
The more you don't make it an issue, the better. The more your students know they can go if they really need to, the better. Those two things alone will almost make your bathroom problems disappear.
It is all part of your classroom discipline and classroom management.