Looking on the internet deeply has found these results:

Windows of the classroom is the most popular phrase on the web.

Windows in the classroom 1775,000 results on the web	Windows of the classroom 1965,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Tom broke a window in the classroom. I saw my reflection in the classroom window. Tom broke a window in the classroom. From our second story classroom window, I could look right down on the Northwest Baltimore Police Station. From our second story classroom window, You broke the classroom window, didn't you? The dreamy kid sitting in the back of the classroom, staring at the window. Remember, Professor, as soon as you used to enter the classroom they had to shut the windows.	From our second story classroom window, From our second story classroom window, I could look right down on the Northwest Baltimore Police Station. Tom broke a window in the classroom. You broke the classroom window, didn't you? I saw my reflection in the classroom window. Remember, Professor, as soon as you used to enter the classroom they had to shut the windows. Tom broke a window in the classroom. The dreamy kid sitting in the back of the classroom, staring at the window.

Windows in the classroom

1775,000 results on the web

Windows of the classroom

1965,000 results on the web

More popular!

Tom broke a window in the classroom.
I saw my reflection in the classroom window.
Tom broke a window in the classroom.
From our second story classroom window, I could look right down on the Northwest Baltimore Police Station.
From our second story classroom window,
You broke the classroom window, didn't you?
The dreamy kid sitting in the back of the classroom, staring at the window.
Remember, Professor, as soon as you used to enter the classroom they had to shut the windows.

From our second story classroom window,
From our second story classroom window, I could look right down on the Northwest Baltimore Police Station.
Tom broke a window in the classroom.
You broke the classroom window, didn't you?
I saw my reflection in the classroom window.
Remember, Professor, as soon as you used to enter the classroom they had to shut the windows.
Tom broke a window in the classroom.
The dreamy kid sitting in the back of the classroom, staring at the window.