What Is the Topic Sentence?

A topic sentence essentially tells what the rest of the paragraph is about. All sentences after it have to give more information about the sentence, prove it by offering facts about it, or describe it. For example, if the topic sentence concerns the types of endangered species that live in the ocean, then every sentence after that needs to expound on that subject.
Topic sentences also need to relate back to the thesis of the essay. The thesis statement is like a road map that will tell the reader or listener where you are going with this information or how you are treating it.

Examples of Topic Sentence:

There were three reasons why I did not enjoy the school trip. Firstly, the journey to our hotel was long, hot and boring. Secondly, we spent all our time in museums doing boring worksheets. And thirdly, we had to go to bed really early.

Topic Sentence: There were three reasons why I did not enjoy the school trip

There are many things that ESL students can do to improve their English more quickly. They can join an after-school club which will give them the chance to practise spoken English while doing an activity that they enjoy. They can also watch films, particularly DVDs with the English subtitles turned on. Best of all, however, is to do plenty of reading for pleasure. Non-fiction in particular is an excellent way of acquiring a strong academic vocabulary

Topic Sentence: There are many things that ESL students can do to improve their English more quickly.