It depends on the state. Oklahoma is ranked 49 of 50 for its k-12 public education system, and we are seeing evidence of this here.

I am a physics teacher in a New Jersey high school (and not even a high ranked school) and I would say that a majority of the teachers are true professionals with masters degrees in education. New Jersey is ranked 2 of 50 though (just behind Massachusetts). We also see teachers salaries around and over $100,000 in New Jersey so it entices more people to become teachers and treat the job very seriously.