A good starting point is a paper by the TESOL International Association (motto: "Advancing Excellence in English Language Teaching") entitled Implementing the Common Core State Standards for English Learners: The Changing Role of the ESL Teacher, from April 2013, (which reminds me, I'd better start to learn to write references again, like, today). A sentence on p2 caught my eye: "TESOL International Association believes that ESL teachers can and should play a critical role in the success of the CCSS." [Emphasis supplied].
"Can and should". One evening a few months ago, whilst still toiling under the desert sun, I watched a BBC documentary about James Brown. It showed a recording of an American talk show he participated in during the late 70s. Another participant was an older, well-dressed white man, who was not identified. He adopted a rather embarrassingly matey attitude towards the Godfather of Soul, several times using the vocative function (to the man who almost everyone else addressed as Mr Brown), "Jimmy".
If this was getting on Brown's nerves, he didn't show it straight away, but when the older guy said, adopting a pained look, of Brown's equal status in America, "You should be, Jimmy...", Brown just lost it. "Should be!" He stood up as if to walk out, controlled himself somewhat and sat down again, (this is James Brown we're talking about). The balance of power in the discussion shifted from the WASP to the Godfather.
So what we're seeing here is the use of modals can and should as a get out. ESL teachers PLAY a critical role in paradigm shifts. Everyone in America IS equal. Let's just look out for mealy mouthed modals delivered by old men with facial expressions of theatrical regret.