What did Franz notice that was unusual about the school that day?

That day, Franz noticed the absence of the routine commotion caused by the opening and closing of desks, repeating of lessons in unison and rapping of the teacher's ruler on the table. The usual hustle-bustle was replaced by a strange stillness that was the characteristic of a school on a "Sunday morning."

Usually, when school began, there was a great bustle, which could be heard out in the street. But it was all very still that day. Everything was as quiet as Sunday morning. There was no opening or closing of desks. His classmates were already in their places. The teacher’s great ruler instead of rapping on the table, was under M. Hamel’s arm. 

There used to be great hustle and bustle in the school on normal days but that day there was silence all about the school. No noise of the opening and closing of desks and of lessons being repeated loudly in unison could be heard.

सामान्य दिनों में स्कूल में बहुत अधिक चहल-पहल रहती थी परन्तु उस दिन पूरे स्कूल में शान्ति थी। मेजों के बन्द करने और खोलने तथा समवेत स्वर में पाठों के दुहराने की कोई आवाज सुनाई नहीं पड़ रही थी।