Role Playing in Chinese Classrooms

I have found that the students respond best to role playing. Accordingly I have been conducting class by lecturing for 40 minutes, then role playing for the next 40. Sometimes the students have no idea what's going on. The students who can understand me very well, often keep quiet until I ask them specifically whether they can explain the reasons or implications; they then respond by explaining what we are learning. That is a real relief. I decided to make sure that everyone comes to class. Apparently some students don't come anymore because they cannot understand my English: it's too fast for them. So in an effort to get them to at least come to class, I announced that I will start taking attendance every day. I also added a very healthy bonus: 70% of the grade will be attendance. This way, I figure, any student who at least comes to class, even if they cannot follow the lesson, will pass. The students who can do well on my final exam will get As and Bs, and the ones who don't come to class will fail! I think class attendance is the most important for a class like mine. The students should be exposed to a Westerner at least. Because I am the first foreign teacher in the department, I think it is important to at least get that going. So, I am told my next classroom will be about twice as many students as have been appearing. That's the way college classes are. They were like that at University of Texas. If they show up, I can make them learn! I can at least get them to laugh or question what they know. Maybe I can get them to cooperate more in class. I want the strong students to help carry the weaker ones.