I don't think Nixelplix is being a pedantic ass about insisting on proper use of the word "theory". When discussing the topic of the diversity of life, and explanations for the observed diversity of life, we're talking about a scientific subject, and the jargon of science is important. A newscaster would be pilloried on BladeForums for referring to a Ka-Bar used in a crime as a "dagger". We knife knuts use more precise terminology when discussing knives because we want other knife people to know what we're talking about. A non-knife person might not care about the difference between a dagger, a bowie, a kuhkri, etc, but if they come in here and want to talk knives, we try to educate them, and (to some extent) insist that they use the right terms.
Similarly, when discussing epistemology, you have to use more precise terms to differentiate between similar concepts. In common usage, a "hypothesis" and a "theory" are used interchangeably, but in science, they're very different. A "hypothesis" is basically an educated guess (note: _NOT_ a "wild-ass-guess") of an explanation for something. If a hypothesis is tested, evidence mounts pointing to it as being correct, it explains new findings, predicts things that we later find to be true, etc, it becomes a "theory". A theory is the strongest form of explanation for phenomena in science. Referring to something
in science as a theory is not the equivalent of saying "Yeah, we think this might could be the way it happens," but rather, "All existing evidence points to this being the way it happens." In this sense, evolution is indeed a theory.
In another sense, though, evolution is a fact. How can it be both? If you're talking about the explanation for why we observe life steadily growing more diverse in the fossil record, you're talking about the "theory" that connects and explains this observation. On the other hand, if you're talking about the observed change in various species that happens in the modern day, then you are observing the fact of evolution happening. (I would be happier, personally, if there were two separate terms in use for this, but alas...) Things like antibiotic resistance in bacteria are observed instances of evolution, but there are
many others, including instances in
plants, insects, mammals... you name it. So, in this sense, it's very proper to teach evolution as a fact... because it happens, and we've seen it happen.
I do know what Codger seems to be saying about not bringing religion into the mix, but the problem is that religious objections are the only objections to evolution being taught as it should be in schools. Creationists keep trying to dress their beliefs up as science (e.g. "creation science" "intelligent design"), but the explanation they're promoting is, quite simply, "God did it." They have a concept, they have an explanation, but it's not a "theory", or even a "hypothesis"; it's dogma. Were it not for religious objections, there would be zero controversy to teaching evolution in schools. This makes it rather difficult to
not bring up religion when discussing the topic.