In order to be clear and convincing, a paragraph should have a basic structure that includes a three parts:
This is called a "claim-evidence-explain" paragraph, or a C.E.E. paragraph.
Sometimes called a topic sentence, the claim states what the whole paragraph is going to be about. Your claim should state a position, not just a fact.
Example:
In The Giver, Lois Lowry shows that removing pain from the world is harmful, because it also removes joy.
Evidence, sometimes called concrete detail, must come from the text that you read. Depending on the assignment you may read one text, or many. Your evidence may be a quote or a summary.
Example:
When Jonas is learning about the past through memories, Lowry writes, "By now Jonas had experienced countless bits of happiness, things he had never known before" (121).
Your explanation, sometimes called commentary, should be the longest part of your paragraph. It is your explanation of how the evidence you just gave supports your claim. This should be several sentences.
Example:
By stating that Jonas has never known life's small joys, the author shows that despite its best efforts, the community has not created a perfect world. Even though there is little distress in day-to-day life, there is also little true happiness. Only through the Giver's memories is Jonas able to experience a fuller life than the rest of the people living in the community.
In fact, it's great to have two or three pieces of evidence in each body paragraph of an essay. Each piece of evidence should have its own explanation, like this: