I came from a very conservative Catholic High School in Peoria, Illinois. I attended Peoria Notre Dame High School where the boys had to wear dress pants, a button down shirt, and a tie. The girls had to wear button down shirts and dress pants. The expectations in college are a little less than what I faced in high school.
Many of you that go/went to a public school have free choice on what to wear to class, and that is how it is in college as well. On a day to day basis I wear sweat pants and a hoodie or jacket depending on the weather. In the spring I rock shorts and a hoodie every day, weather pending of course. Chicago is known as the windy city so i would bring a few jackets. To be honest no one really cares what you wear just show up to class.
Although the professors do not mind what you wear it is important that you take something into account. When you have presentations to give in class it is important that you ask your professor if your attire will be graded. As a business major my attire is graded in some classes and on most presentations. Most professors will not care, but you should clarify before your grade is effected adversely.