In the shadow of a giant, inflatable rat, members of the union marched outside The Post headquarters in downtown, D.C., calling on readers to cancel their subscriptions.
"We are the teachers," they sang. "The mighty, mighty teachers."
Union President Nathan Saunders says the newspaper's editorial board is too quick to blame teachers for problems in the city's schools.
"All teachers have been vilified and painted as bad," he says. And Saunders says The Post's ownership of Kaplan, the test prep and online education company, creates a conflict of interest for the newspaper.
"The Post must disclose every single time that it talks about education that it is an owner that provides the majority of its profitability in the testing area," he says.
Fifth-grade D.C. Public Schools teacher Francesca Dixon says it's time for editorial writers to consider the obstacles teachers face every day.
"We haven't looked at poverty rates," she says. "We haven't looked at the emotional health of the children, we haven't looked at the fragility of families. All they're doing is saying it's the teachers' fault."
In a statement, a spokesperson for The Washington Post says The Post is entirely separate and independent from Kaplan, the editorials represent the views of the individuals responsible for the page, and readers can choose to agree or disagree.