Most kindergarten classrooms have the bathrooms right in the classroom. But I agree the parents need to have it written down on all of the forms that frequent visits often 10 mintues apart at times is normal and child should always be allowed to go if she feels she needs to.

And for sure make sure child knows how to change out of wet/soiled clothing and clean herself up as teachers are not allowed to do it. And then send lots of changes of clothes.