Even before they were winning elections, conservative Republicans were making education in general and teachers in particular their whipping boy. They were suspicious of the well-educated, harboring underlying beliefs such as "you don't need no college education, you need COMMON SENSE! " Common sense was something that they believed they had in abundance whereas those who believed in science and education had little of it. I have heard "college boy" used as a slur in my conservative area.
Conservatives are distrustful of education because they believe that it may make students question or challenge their "traditional conservative values," and don't want critical thinking taught in the schools in any form. They are generally opposed to any increases in funding for education, believing that it will be channeled into salary increases for teachers, who they believe already make "too much money." Another choice chestnut that I've actually heard voiced by an adult Sunday School teacher is that "A good teacher can teach in a BARN!" I walked out of that class after hearing that one, and never returned to it...
The stupidity, it burns, it burns!