Both should be taught, I agree, BUT on entirely differt grounds.
Evolution as science with an exceptionally firm scientific and testable footing, albeit not 100% unproblematic. Creationism as part of teaching about religious beliefs, where all major world religions as well as Atheism and Secular Humanism should receive their share of the time. Also the debate on creationism and evolution in itself can serve as an example of a complex issue, where people disagree, and to explain the scientific method.