Restricting ourselves for the moment to determining which we should be teaching as established science (as opposed to Religious Studies), it appears to me that the theory of evolution is more closely derived from extant data and scientific principles than the conjecture of Intelligent Design (or whatever it's called this week). Hence, Evolution should be taught as having a factual basis; Creationism should not.

I speak as someone who hangs around with a lot of scientists. Your mileage may vary; if so, please respond.