Darwinism is the only scientific theory, hence why it alone is taught in science textbooks. Intelligent Design is an untestable and vague explaination which makes no specific claims about the history of life or the mechanisms of it's change over time that can be tested.
Equally Intelligent Design of weather is not taught in school textbooks. Only naturalistic mainstream meteorology is taught. Even though Intelligent Design of weather could be true. It's just untestable.
Perhaps Karl Rove will lecture on the subject after he retires from Government Work; he was responsible for Katrina, according to some.
If this is the truth and I doubt it, why are the evolutionist so afraid of having both sides of the story told hmm?
If you are so right and if your theory is so correct, then you have no reason to object to open debate in a classroom.