YUQING COUNTY, China — With the fiery zeal of a preacher, Xie Hong addressed her class of 50 fourth-grade students, all in matching red tracksuits.

“Today’s life is rich, blessed, happy and joyous,” she said. “Where does our happy life come from? Who gave it to us?”

In Ms. Xie’s classroom at the Workers and Peasants Red Army Elementary School, there was only one correct answer, and she had worked tirelessly to ensure her students knew it.

“It comes from the blood of revolutionary martyrs! From the Red Army!” said a 9-year-old boy, Li Jiacheng. The class burst into applause, and Ms. Xie beamed.