How can we change the reprehensible behavior related to immodesty in dress and shoes inside and outside of school, while providing legitimate religious proofs for its prohibition, especially when it concerns older female teachers?

The 'awrah of a Muslim woman with another Muslim woman, according to the majority of scholars, is what is between the navel and the knee. The covering garment must be loose, not revealing the size of the limbs, and opaque, not showing the skin. If the garment is tight or transparent between the navel and the knee, then it is forbidden. As for non-mahram men, the woman's entire body is 'awrah, according to the preponderant opinion, and she must cover her feet from them, based on the hadith of Umm Salamah, may Allah be pleased with her, with the Prophet, peace and blessings be upon him, regarding women lengthening their garments.