Driving on freeways requires an aggressive attitude.I can see that "Driving on freeways" is the topic, but I don't understand how "an aggressive attitude" can be the controlling idea. It is not an idea at all. (Perhaps you could elaborate on what is meant by "controlling idea".)
As for sentence 5, try:
Participating in class discussions in English is a special problem for international students.It seems that each of your sentences does itself express an idea.
Participating in class discussions in English is difficult for international students.
International students have diffulty participating in class discussions.
Let's talk more.
(Don't thank me yet. I haven't helped you yet.)