Topic Sentence: Tell us tells us the main idea. It is usually the first sentence in a paragraph.

Supporting Sentences: Helps the reader understand the main idea by giving more information about it.

Here it is an activity that we did in clases about the topic sentence and supporting sentences:

I think that this activity that I did in class was really interesting, because I could learn more about the parts of a paragraph, how we can recognize them and how they can help us to find the main idea of a certain paragraph.