Why does the stillness in the classroom seem strange to Franz?

The stillness in the classroom seems strange to Franz because it contrasts sharply with the usual lively atmosphere of learning and interaction among the students. In this final lesson, the somber mood heightens the sense of loss and resignation, making the silence feel heavy and oppressive. Franz is acutely aware of the significance of the moment, and the quiet amplifies his feelings of regret and nostalgia for the carefree days of childhood. This unusual stillness serves as a poignant reminder of the gravity of their situation, marking the end of an era for both him and his classmates.