The D.C. teachers union is telling its members to wear red on Wednesday to show support for teachers in Chicago who are striking over their contract.

The dress-code message came Tuesday evening on the Washington Teachers' Union's website and through a Twitter post from its president, Nathan Saunders: "WTU Delegates voice support of Chicago Teachers Union. 'Wear Red to school and Support Chicago Teachers Union' on Wednesday.

"Teachers across the country must join together in solidarity to ensure that teachers — who spend every day educating our students — are valued and respected for their work," Saunders said in an email Tuesday. The D.C. union has supported its counterpart in Chicago, which began its first strike in 25 years on Monday, the beginning of the second week of school.

The nation’s third largest school district, Chicago serves nearly 400,000 students who are without classrooms to attend for the third consecutive day Wednesday.

After 10 months of negotiations, the Chicago school board and its teachers union remain divided on evaluations tying students' test scores to ratings — and issue which should sound familiar to D.C. residents — and other job security measures.

While Chicago teachers are paid well above the national average with an average annual salary of $76,000, even a 16 percent raise over four years couldn't assuage other conflicts in the contract.

Read the full statement of support that Saunders provided The Washington Examiner on Tuesday:

Washington, D.C. (September 10, 2012)—Statement of WTU President Nathan Saunders in support of striking Chicago Teachers Union members.

“We support our fellow teachers and union members in Chicago as they take a stand against unfair compensation, inadequate benefits and punitive evaluations that place too much emphasis on student test scores which will undoubtedly lead to a less stabilized environment for teachers and students.

“In just three short school years, D.C. Public Schools has dismissed nearly 400, or 10 percent of teachers, since implementing its IMPACT teacher evaluation system that, until recently, was heavily based upon student test scores.

“It is the very nature of educators to want to create a better school system for the children, families and communities they serve. Teachers across the country must join together in solidarity to ensure that teachers—who spend every day educating our students—are valued and respected for their work.”

The Associated Press contributed to this report.