A large portion of americans would disagree.
A large portion of Americans aren't very well educated in the topic.
I know that popularity does not equate fact, but when in the field of science over 99% of the people who ARE experts in the subject agree that evolution is fact, what reason is there even to say otherwise? All evidence we currently have supports it. The only argument against it are either misconceptions or simple conflicts of previously held beliefs.
Whats wrong if it is taught and giving student the right to believe it or not?
They have the right to believe it or not, but it should be taught as fact, because again, it IS fact. Not "believing" in evolution (and I put that in quotes because it's not something that requires a belief as we have mountains of evidence and have demonstrated its properties in numerous ways in different fields) is, quite frankly, ignorant. There is no legitimate reason to disregard evolution. The only reason people do so is because some old book of shepard's stories tells them that some magic guy in the sky created everything as is.
And, EVEN IF, by some ridiculous coincidence, the world DID just "poof" into existence 6000 years ago, that STILL doesn't invalidate what the theory of evolution states.
Long story short, there is absolutely no reason to not accept evolution as fact. Until the as-of-yet nondiscovered (if ever) piece of evidence comes up that so irrefutably contradicts the theory of evolution, not accepting it is asinine.
You have the right to believe that it's what we call gravity that keeps us on the surface of planets and not some other force.