1. US university classrooms are diverse due to varying teaching methods, curriculums, and differences between undergraduate, graduate, private, and state-funded schools. 2. Active participation is encouraged through classroom discussions guided by teachers, student questioning, and student-led seminar presentations and discussions. 3. The teacher-student relationship is multifaceted, with teachers taking on roles as counselors, friends, and authority figures who expect deadlines to be met, while students must adapt their behavior appropriately.