Mr. Ross had only planned to demonstrate the power of Nazi control with his teaching for one day. But the next day, the atmosphere in his classroom was different than it ever was before.
Recall that the night after the first day, Mr. Ross told his wife that he had to move on and start teaching about Japan. He explains that the next day he forgot his notes on Japan and was running late to his class. When he got there, he was shocked to see all of his students already there. Students typically straggled in late, but that day he was the only one who was late. The students had also made sure that their desks were all neatly arranged and were sitting with straight posture, just like Mr. Ross had taught them the day before. Everyone in the class was quiet, waiting for his instructions.
Mr. Ross reflects that this behavior was unusual because the room was only ever still and perfectly quiet when he was the only one in it. All of a sudden, after one day of the experiment, the class was more alert, attentive, and disciplined. This overnight transition in behavior shows how powerful the fascist-like behavior Mr. Ross was demonstrating is.