Como dizer "Sentem-se em seus devidos lugares" em inglês

A teacher would certainly say something like that
Please, sit in your assigned position/chair/seats.

or "please sit on your chair/seat'' (would do, assuming it´s not the first day of class/school).

Each teacher has a method, some assign chair alphabetically, others may go rearranging througout the year.

A professora pediu gentilmente aos alunos que se sentassem em seus devidos lugares de acordo com o espelho de classe.

The/our teacher kindly asked the students to take their (designated) seats/chairs, according to the alphabetical order/the order in the rollster.

Há uma tradução próxima para espelho de classe?

Espelho de classe pode ser expresso por "a seat plan" also classroom "seat chart", but to learners/students, classroom "seat plan" seems more usual.
I added classroom to specify it, since there are "airplane seatting plan" and others.

Thanks for the reply

You're welcome.