 Hello, this is Dan. You've probably heard many times how important a topic sentence is, but do you know what it actually does? Listen to a couple of my students, Tom and Mary, discuss a homework task I've set them about topic sentences to find out more. Hi Tom. Oh, hey Mary. Have you finished the class work? Daniel asked us to work on. Oh, you mean the one asking us to select the right topic sentence for a paragraph? Yes. Have you got any ideas? Yes. The topic of the passage is China's age and population. Take a look at the paragraph. Don't you think A is the best choice? It has the key words such as China and elderly people. But I remember Daniel told us that a topic sentence expresses the main idea of the paragraph. It seems that sentence A cannot fully explain what the paragraph is discussing. I see your point. But suppose A is wrong. What about B? It is focusing on the population policies and the paragraph criticizes the policies. Yes, it is. But don't you think this topic sentence is a bit too general for the paragraph? Oh, I remember Daniel told us that a good topic sentence shows how the key idea of the paragraph is connected to the thesis. Then what is the thesis of the topic? Let me check. The thesis statement can be easily found in the introduction. Okay, I found it. The thesis of the topic is this problem is particularly serious in China because of the government's inconsistent population policies and the changing attitudes of young couples towards having children. Great. It seems that C should be the right one. The idea echoes the first point mentioned in the thesis. What is that? Do you see the key phrases here? Major calls, governments inconsistency and population policies. I'm still not very sure about this one. Shall we go to Daniel and check with him? Good idea. Let's go. Oh, there he is. Hello, Daniel. Can we talk to you for a while? Hello, Tom. Hello, Mary. Sure. How can I help you? We've studied the three choices of topic sentence given here. We'd like to check with you the correct answer. Hmm, which one have you chosen? We are quite certain that option A is not the topic sentence of the paragraph. Hmm, no. A is not the right one. And Tom said option C is the correct one. Tom is right. Remember, the correct answer is C because it supports the essay's thesis statement, advises the readers of the subject to be discussed and how the paragraph will discuss it. Remember, a well-organized paragraph supports or develops a single controlling idea which is expressed in a sentence called the topic sentence. Okay. That's all from me. And don't forget, you can get more help with your essay writing and topic sentences from the SIL website, as well as the teacher at the SIL Help Desk.