Expressivist pedagogy rose as a response to the dominating current traditionalism. The latter mostly focused on writing for the academy in certain standard formats, using correct grammar. However, it did not fully comprehend all the pieces of the rhetorical triangle and so expressivism stepped in to try to fill that void. There must be communication and interaction between four things: the writer, the audience, the message and language. Usually, the writer will be found at the center of a triangle built out of the other four. This means that the writer is the central focus – he/she has the highest value in the text being creating. By allowing everything to revolve around the writer, the writer is able to use their voice to make their point heard.
Expressivist pedagogy further shook things up by invading classes with a more process-based perspective. They turned to freewriting, journaling and peer-revision to help writers develop their own voices. Whether students were writing to inform, persuade or relive past experiences, they are encouraged to consider their roles as both the see-er and the do-er, the observer and the participant.
Meanwhile, in between my discussion of what expressivism really is, I will name drop about lots of people in the field and the books that they have written (of which I have no doubt read almost everyone) as well as tell you all of my significant contributions to the cause. Perhaps you shall want to check out more of my work?