The American Classroom
You may find that teaching styles in the U.S. are much different than those in other countries. Teaching in the U.S. is often more interactive and less dependent on rote memorization. Students regularly ask questions of the faculty or offer constructive criticism of the lecture. This is encouraged as professors prefer discussion and debate rather than passive silence. You will also notice that the students and faculty tend to dress rather informally. In addition, faculty will have open office hours for students to come by and ask questions.
Class sizes tend to be smaller in the US than in other countries. Although first-year students may have a few large classes, most classes are small, with 15 to 45 students. The large lectures will often have small discussion sections run by teaching assistants or faculty. Discussion sections review the material presented in the main lecture, supplement it with additional material, and provide an opportunity to ask questions. Generally, you will receive one credit for each hour you are in class per week. For example, a three credit hour class meets for three hours each week.
Your grade in most classes will be based on your scores on tests, quizzes, projects and papers. If the class has a discussion section, active participation can improve your grade. The better the professor and teaching assistants know you and your work, the better they will be able to assess your progress.
adapted from: The International Student Guide to Studying in the USA