Bruising political fights are usual business in Becky Debowski’s eighth-grade social studies classroom. From a model Constitutional Convention to a bare-knuckle debate in Congress over slavery, she regularly has students assume roles of partisans throughout American history, like Abraham Lincoln and John C. Calhoun.

After the exercises, the class comes back together to debate whether the nation lived up to what the state of Michigan calls “core democratic values,” such as equality, liberty and diversity.

For decades, the values have been the heart of the state learning standards in social studies, a doorstop of a document that guides what teachers of history, civics, economics and geography cover in their lesson plans.

“I’m really proud of my students,” Ms. Debowski said. “They can handle the complexity.” So she was angry last year when she learned of a proposed revision of the state standards, in which the word “democratic” was dropped from “core democratic values,” and the use of the word “democracy” was reduced.