In it's who-knows-how-manyth anti-union article, Charter school teachers not bound by union the Editorial Staff writes that "...Educators hired to teach in Oklahoma's charter schools can choose to join a union or remain independent." Implying that this is not the case in the Oklahoma public school systems.
Oklahoma is a "Right to Work" State, and therefore teachers are free both to join unions and to refrain from joining unions (see Okla. Const. art. 23, § 1A). Once again, they state something that can easily be refuted because it simply is not true.
If you want to read a really good article on Charter Schools, I HIGHLY recommend Sarah Knopp's fine article Charter schools and the attack on public education.