Is it illegal for a teacher to refuse to allow students to use the washroom in Alberta?

Teachers are allowed to not let a student use the washroom is the student does it all the time in the same class. If a student doesn't do it everyday and the teacher still doesn't allow it, then it's illegal. Sometimes students will try to use the washroom everyday for most of the period and if the student does that, then the teacher realizes that the student is only asking to use the washroom just to miss class.