Hi Macuahuitl,
In science class we teach the current understanding of science, at an age appropriate level, of course. The current understanding of science is that the earth and universe are old and that man and all other life evolved from earlier life forms. What you're proposing is to not teach science in science class.
Furthermore, "It is the height of Bigotry to have only one theory of origins taught in our schools" (Clarence Darrow, see
http://www.baptistpillar.com/bd0354.htm - although this quote is often refuted, it is still at the height of bigotry).
I can see why it is "often refuted." For one thing it seems an unlikely thing for Darrow to say, since at the Scope trial that's precisely what he was advocating, teaching the scientific theory of life's origins, of which there is only one. For another, likening it to bigotry seems unlikely for Darrow, since he actually saw the situation as a violation of the separation of church and state. Poking around I found
Clarence Darrow Misquoted by Creationists at TalkOrigins, take a peek.
If there were more than one scientific "theory of origins", that would imply that no scientific consensus had developed and that there was no agreed upon scientific understanding, and it would be inappropriate under most circumstances to teach either one, other than to perhaps take note of the uncertainty. It's not that there's any inherent objection to teaching two or more different theories of the same natural phenomenon, but even at the high school level this would be challenging and confusing for most students and I think it should be left out of formal curriculums, leaving teachers to decide whether any particular unresolved area of scientific study should be introduced.
--Percy