Student handbook says differently?

Some staff members of Artesia Intermediate school are dress-coding students when their skirts are not below the student's hands on their sides. The student handbook for Zia intermediate states ''The hemline for shorts, dresses, and skirts must be of sufficient length to cover body parts in a manner appropriate for school.'' and the Artesia Public schools student dress code says ''The hemline for shorts, dresses, and skirts must be of sufficient length to cover body parts in a manner appropriate for school.'' As well, why are teachers dress coding students even though the 'rule' they are breaking is not in any dress code applied to them?