In my school we were treated as adults and were expected to behave accordingly. Bathroom breaks did not require permission.

Delay students from using the bathroom until student has answered the question correctly

Deny access to the bathroom anyways

Student Defecates in the classroom

We were allowed to go whenever we wanted, but I tried to wait until there was a task/break so I wouldn’t miss important info. Kids in Norway are treated like adults, but of course if you’re childish and use bathroom breaks as a means to skip class, then you’ll always hear a “no” from the teacher.

If I were to ask to use a toilet in a different country my teacher would probably chuckle and tell me to simply use the one down the hall instead.

It’s tough. A lot of kids use it to goof off or vape/do drugs in the bathroom. Even in middle school.

There are definitely kids you can trust, but many at least abuse it to goof off.

Edit: Forgot to state, US.

US, similar to others, I had to ask permission and it was always granted.

I can recall once I ran to the bathroom for an emergency without permission. My teacher checked in with me later and discretely to make sure I was ok. Most of my teachers over the years were reasonable people who saw their students as human beings, so I wasn’t worried about getting into trouble.

There was a student in my class one year who had to get an escort if he needed to go anywhere during class because he had a history of doing dangerous things. He tried running away, he wandered into a janitor closet and started randomly mixing chemicals together, he went into the teacher lounge and started eating their lunches, he went into the girls locker room and was found rifling through their gym bags. So yeah, from simple liability and the protection of other students, he wasn’t allowed to leave the classroom whenever he asked.

I don’t know about other countries, but in my own, teachers have their own designated bathrooms. As in there are girl’s bathrooms for girls, boy’s bathrooms for boys, and a third kind of bathroom with a logo not for girls or boys but for teachers (regardless of gender). If I were to use one of these teacher-designated (and yeah it has happened before), I would land myself in more trouble than if I used the boys’ bathroom. This being an age where gender norms are being challenged, being caught red-handed once, I made a remark about “sexually identifying as a teacher” which only caused my punishment to double (I even remember asking if the floor or my skirt would be a better option on a bad bladder day and got a blunt yes). Moral of the story, don’t get between teachers and their bathrooms, no pun intended.

Fair number of answers, no one saying what country they are from

US here, we had to ask but it was basically always a yes.

Reasons for a no:

Middle of a test

Middle of explaining something important, then you might be asked to wait a few minutes

If you were just abusing the system asked always asking just to get out of class they would probably start saying no. If you had a medical issue you could always meet the teacher after class or before school and say you have a medical issue that prevents your from waiting. It it was a sudden thing like diarrhea… Well just get up and go.

You had to ask permission, but only so you could be given a toilet pass - this was so if any other teachers or staff saw you walking around you had evidence that you were allowed to be out of class.

In our kids’ elementary school, the rule at the start of year was that kids tell the teacher they have to go, then they simply go. Notifying the teacher is mandatory, 'cos they are responsible for the kids, they need to know where they are.

This was slightly changed since, because of bullies. While the vast majority of kids can go to the bathroom whenever they want, bullies don’t: they can only go alone, or supervised. So if there’s anyone else out, from any class, they have to wait. If it is urgent, a teacher or another adult will go with them, and stand by the door, close enough to intervene if need be.

Australia, we had to ask until uni

When I was in school you had to raise your hand during free time to ask. If you raised your hand while the teacher was talking they would ignore you. There was maybe like a 50/50 chance the teacher lets you go to the bathroom and kids that were noisy generally were told no more than yes. Quite a few instances of kids wetting themselves and the class was merciless to them after. Had a whole list of kids who wet themselves.

In elementary school you needed to ask and take some wooden tag from the class room. Couldn’t go if the tag was gone, so only one person at the time. In middle school you don’t ask, you just say you’re going.

Netherlands btw

Switzerland: Generally you are only allowed to go during breaks and if you forget / don’t have time due to switching buildings you are told to suck it. Starting a certain age girls are allowed to go whenever, but only some teachers allow it in practice. During breaks though, I never had to ask a teacher.

No bathroom breaks during classes.
You can’t leave classroom without good cause.
When you ask for permission to use the toilet, there are low chances to grant it. Unless you are a girl, gender bias.

Good luck to find an empty toilet, if you have “shy bladder”, between classes.