Help me write topic sentence

In European universities, students are not required to attend classes. In fact, professors in
Germany generally do not know the names of the students enrolled in their courses. In the
United States, however, students are required to attend all classes and may be penalized11 if
they don't. Furthermore, in the European system, there is usually just one comprehensive
examination at the end of the students' entire four or five years of study. In the American
system, on the other hand, there are usually numerous quizzes, tests, and homework
assignments, and there is almost always a final examination in each course at the end of the
semester