Mr. Raymond explains to Scout that the world isn't so cheerful and kind like she wants it to be. Inside the courtroom is a chance to realize this. The courtroom will give Scout the most accurate insight available to understand not only the real world, but the citizens that live in her town.
In his majority opinion on Tinker v. Des Moines, Justice Fortas argues that free speech would not truly exist if people could only express their opinion in a designated place.