After all, very little in the ordinary curriculum is completely uncontroversial, accepted as truth by everyone who cares, and supported by eyewitness testimony. So, go further, folks. There's more to biology than evolution, of course. For example, the germ theory of disease is not universally accepted. Christian Scientists believe that disease is a matter of incorrect thinking, and can be overcome by the right worldview.
Equal time is in order here.
Obviously, the idea of standardized spelling has to be questioned. President Andrew Jackson pointed out that it's a poor mind that can think of only one way to spell a word. Indeed, the way we spell is based on a mere theory, an agreement, and there are a number of equally valid theories out there. Students should be taught British as well as American spelling, and encouraged to choose whichever they think makes more sense. Granted, this might make it a little more difficult for Kansas students to cope in the larger world outside the Kansas school system, but if we can afford that risk in biology for the sake of intellectual freedom, we certainly can afford it in reading.