проверьте, пожалуйста, правильность написанного:

School 291 is comprehensive (общеобразовательная школа имеется в виду. какое слово лучше подобрать?), she has about 500 students in 11 classes. Each school class is divided on 'a', 'b', 'c' and so on. 10 and 11 classes are divided into profiles 'humanitarian' and 'mathematical'. In our school lessons are from 9 AM to 3 PM. Junior school is open until 13:00.
The 291 has a system of duty (систему дежурств). High school students watch that  everyone has had a change of shoes and no one has sitting on the windowsills.
In our school is forbidden to wear jeans, being late and chew the gum.

на мое усмотрение  тут всё  верно )