The theory of Evolution is grounded in the known science of how organisms mutate/evolve, and of course, on the fossil records.
The theory of Creationism is based on the scripture of just one religion out of many religions. If we force teachers to discuss Creationism in Physical Science class we will be forced (lawyers ... you know) to discuss the origins of life expoused in the scriptures of the other major religions (except Buddhism, which doesn't have one).
Think of it ... the NC House of Representatives passes a bill that requires one week of Creationism in all NC classrooms. The Christians, Muslims, and Jews are happy at first. But before you know it, the local Islamic and Jewish groups have lawyers filing suit over the minute differences in the interpretations of the origins class. They want their specific versions taught, as well. They say "it's only fair", and they'd be right, actually. Then the Hindus protest the schoolboard meetings and they eventually get a lawyer ... you get the idea, I'm sure.
Isn't it better to stick to accepted scientific fact and leave mythology out of it?
With respect ...
Minh