What is the ruling on young women sitting in the front and young men in the back during lectures, and is the teacher, who is able to reverse the arrangement, sinful?

Mixing between genders in studies is forbidden and leads to corruption. It must be prevented by separating male and female students. However, if separation is impossible, and the girls sit alone in the front rows while the young men are behind, this is less problematic than them mixing in one row, which could lead to looking and touching. It is better for women to be behind men in the rows. The best rows for women are the last ones, and the worst are the first ones. If the girls are not adhering to the Islamic dress code, the teacher must prevent them from advancing so that young men do not look at them. The teacher sins by allowing them to advance if he is capable of preventing them. As for girls simply advancing while properly covered, this is not considered a reprehensible act for which the teacher sins by not condemning it.