What are the three most important things teachers should do/know to improve the learning considering the remarkable research you have done?

“When they walk into a classroom, to say, ‘My role here today is to evaluate my impact’ and then the students are the beneficiaries.  This means you need an answer to what you mean by impact, you need to know that ALL students are gaining this impact, you need to articulate impact about what, and ask about the sufficiency of the magnitude of this impact!  And given the above, to have these questions and answers critiqued by fellow professionals” (John Hattie, personal communication, August 19, 2018).