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

Franz noticed that instead of hustle-bustle, that used to happen in the school every morning, there was a silence in the school and everything was so still and there was no usual tapping of the ruler on the table that his teacher used to do. Also, some villagers were sitting on the benches at the back of the class. Mr. Hamel was wearing clothes that he used to wear on special occasions.