I agree with the second post. Standards of appropriate dress may vary greatly, even from one school to another. It should be easy enough to discover the standards considered appropriate at any given school, especially if the school has a web site with photos of its faculty. Since most people will have beens students at some point, almost anyone can be consulted about what is considered appropriate in a particular area of the country in a particular era. You probably can't go wrong if you simply dress as you would for any "professional" position.