As an international student, when you plan to come to US, you should probably start to accept and understand the many cultures there. America is a free country that embraces various religions, cultures and nationalities.
Even though I thought I understood American culture when I was in China, I was shocked by many aspects of it once here, and spent a long time getting used to it. First, I would say is the language gap. Lots of international students here feel even if you get a high score on the TOEFL or SAT exam, you still feel it is hard to communicate with native speakers, because they speak in a really fast speed and sometimes you can’t catch up. Also, some international students can’t get along with Americans because they can’t speak clear English and they don’t have common topics, so staying with Americans make them feel awkward and stressful.
Second, the classroom environment will be different. The class could be fun or also could be boring which depends on the relationship between the professor and students, and how students are involved in the class. International students, from my perspective, are not as active as American students. Americans are brave enough to ask questions in the class and discuss with the professor while international students may not. In addition, in the American class you will encounter various professors from different countries, this means they will have different accents.
To sum up, what I mentioned above are just some of the phenomenon that happens at an American university when you really live and study here. It may take you a while to accommodate to the cultures and differences. However, you will find you've been part of them and will get accustomed and enjoy it!