NOTE: Only the site Admin can invite a teacher and edit another teacher's profile.
If a teacher needs to write stories for children in multiple classes, you are able to add the staff member to more than one class.
However, you can only select one class when you first invite the teacher. So you will need to wait for the teacher to accept their invite before you can assign multiple classes.
To assign the teacher to classes, you will need to Edit their Profile.
You can simply select which classes they belong in by ticking the check boxes in the drop-down "Class" menu: