An original fiction passage set in the nineteenth century.
After the last lesson, Tom went back for the slate he had left beneath his desk. The schoolroom was empty, and the winter dusk had blurred the windows into dull squares. He knew the rows of desks by heart, yet the room seemed to stretch beyond its walls. When a loose shutter struck the building, he clutched the slate and hurried towards the door.
Identify the sentence which suggests that the empty schoolroom seems bigger to Tom than it really is.