. >> reporter: including cara stoltenberg. >> what do we want? >> when do we want it now?porter: fury over those flat and falling wages helped spark a movement, one that in the last 18 months has swept through conservative red states. >> enough is enough! >> reporter: and liberal blue cities as tens of thousan o teachers walked off the job. >> we feel that the expectations for them have risen, and their pay has not really kept up. >> reporter: dana goldstein is an education reporter for "the new york times" and author of a 2014 book about the history of teaching. she says low pay has been a problem since the early 1800s, the time when most teachers in america were men. >> when it came time to have universal public education for all american kids, horace mann, the father of our public school system said i have an idea. let's bring women in as teachers. then we can expand public education and it will not cost quite as much. >> reporter: because we don't have to pay women as much? >> exactly. at that time it was legal. you could pay women half as much. >> reporter: but goldst