1.The topic sentence introduces what the paragraph is talking about and limits the information that can be given in the other sentences.Students often mistakenly begin a paragraph with sentences such as:  I want to tell you about .The Topic Sentence
A paragraph is a number of sentences written about the same topic.The other sentences add information to the topic and are called supporting sentences.The main idea of the paragraph is usually given in the first sentence--which is called the topic sentence..or This paragraph is about .These are not proper topic sentences as they do not really introduce the topic.They introduce your intent or your writing plan, but not your topic.........