Is it permissible to lie to one's father by claiming to go to the hospital in order to be absent from mixed-gender schooling due to sins, and how can one lower their gaze from female teachers in a mixed-gender school, and is it permissible to look only as much as needed?

Mixing of genders in educational institutions is prohibited, and one must transfer from mixed schools. It is permissible to use tawriya (equivocation) and ma'arid (allusive speech) out of necessity or for a benefit. It is not permissible for a man to look at a non-mahram woman except out of necessity or dire need. The student must lower his gaze. If the student perceives in himself a slip or the beginning of deviation, he must refrain from attending.