We try to teach biology without talking about evolution..

Sorry for my off-topic and lack of info about some ills of the day, but is this really being done now in schools?

Yes.

I teach evolution vs creationism as a writing project in my university freshman comp. class.

When I inquire into my students' backgrounds, it turns out several have had no instruction in either Darwin or the Bible.

Yes, and the reason is the "free market."  Textbook publishers must cater to the religious right, or lose a huge chunk of marketshare.  Basically, if Texas won't buy the books, it's not profitable to publish them.  So even communities where evolution is widely accepted find their choices limited.
The "Invisible Hand" is once again providing the magical, optimal solution for all of us. In our society, greed-for-profits trumps over any notion of truth, justice and honor. The bottom line is therfore, that our system of free-for-all self-governance (the Adam Smith approach) forces us to swallow stupidity (Creationalism, Intelligent Drugsign) and to smile as we do it.