Teachers greet students before classes normally Sit down and order, emphasizing repeatedly Stand up and vice versa several times. To enable students to follow the command.
Teachers greet students before regular classes with an emphasis on command Sit down and Stand up repeatedly and alternately several times. Students race to follow orders.
I greet the students before class as usual with emphasis on order and Sit down Stand up repeatedly and alternately, many times, to make the students to compete following orders.