Actually, I suppose they can teach just about any pseudo-science they want. A deranged school board could banish evolution and teach Lysenkoism (Stalin's favorite biology theory). The only constraining rule (other than a state's own constitution) is the First Amendment. They can't use a science class to establish a religious doctrine.
I guess that's the difference between the Canadian and the US educational systems. The school boards here can determine which classes are taught at which schools and what level of knowledge can be taught in which grade, but they cannot change the content of what is taught. No 2+2 = 9, no '2 hydrogen atoms combines to make iron', no 'the atmosphere is made up of oxygen', no Lysenkoism.