When the video starts shooting, the camera should be aimed at the corridor outside the classroom. It should be shot with a mobile phone, because the pixels are not very high, and the video can clearly spread the voices of students in the university campus and the teaching building corridor.
Then the camera turned to a classroom, as if it were behind the classroom. The window was wide open, and a girl in a blue T-shirt looked out from the classroom window. If you look from the outside to the inside, the girl is looking at the scenery from the window, which is a common action of students.