How do you "teach the controversy" when there really isn't one? This op-ed, published by The Guardian in 2005, is perhaps the best explanation of why you shouldn't. Regardless, proponents of intelligent design are wasting our time and our money, and they are putting the future of science education, and of your children's education, in jeopardy. All in pursuit of the fantasy that an unscientific religious theory becomes respectable and worthy of equal time just by donning a lab coat. Remember that, if you are dragged into a movie theater by a creationist friend when Expelled is released.
Intelligent design no more deserves equal time in science classrooms than those who claim they can explain the origins of life to us after binging on peyote and magic mushrooms.