The actual wording is this: Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof
Now, to me, that says that the government can't force us to learn about Creationism because it is a religious concept. And in that case they would be 'respecting an establishment of religion'
That's just how I see it.
From a purely academic perspective, Creationism holds no scientific value, and so should not be taught in science classes. If schools want to offer a theology class, or something similar, where it can be taught as an elective, I'd have no problem with it.