The 800 teachers and staff of Chicago’s Noble charter school chain is working to form the largest charter teacher union in the country.

They would not become the first charter union in the country, or even in Chicago. In fact, the Aspire network of charter schools just averted a strike by their own teachers’ union by agreeing to wage increases, shorter workdays, and, apparently, occasionally listening to their staff. Like the proposed Noble union, the Aspire teachers belong to the Chicago Alliance of Charter Teachers and Staff (ACTS), a group affiliated with the American Federation of Teachers.

The Noble chain is one of Chicago’s most prominent, founded in 1999. Its investors include Governor Bruce Rauner, the billionaire…