Understanding What You Read: Main Idea and Author's Purpose

When you read a passage, you are looking for more than just the words on the page. You are looking for the big idea the passage is mostly about, the small details that support it, and the reason the author wrote it in the first place. This lesson shows you how to find all three.

The main idea is the one big point a passage is mostly about. Every other sentence in the passage helps explain or support this one big point. If you had to tell a friend what the whole passage was about in just one sentence, that sentence would be the main idea.

Sometimes the main idea is stated in the first or last sentence of a paragraph. Other times you have to think about all the sentences together and figure it out yourself.

Supporting details are the facts, examples, and small pieces of information that back up the main idea. They answer questions like who, what, where, when, and why. A good detail helps prove or explain the main idea, it does not just repeat it.

Try this passage: "Max is a very helpful dog. He carries the mail from the front gate. He wakes his owner up every morning. He even fetches slippers before bed." The main idea is that Max is a helpful dog. The three supporting details are carrying the mail, waking his owner, and fetching slippers.

Every author has a reason for writing. There are three common reasons, and you can remember them as entertain, inform, and persuade.

• An author writes to entertain when the passage tells a fun or exciting story.
• An author writes to inform when the passage teaches you true facts about a topic.
• An author writes to persuade when the passage tries to change how you think or act.

Ask yourself: does this passage make me laugh or feel excited, does it teach me something true, or does it try to talk me into believing or doing something? Your answer tells you the author's purpose.

Read this short passage: "Recycling helps our planet. Recycled paper saves trees. Recycled cans save metal that would be thrown away. You should start recycling at home today." The main idea is that recycling helps the planet. The supporting details are saving trees and saving metal. The author's purpose is to persuade you to recycle.

Once you can spot the main idea, list the details, and name the purpose, you understand what you read instead of just saying the words. This same thinking works for stories, news articles, and even instructions.

Main idea: The one big point a passage is mostly about.

Supporting detail: A fact or example that explains or backs up the main idea.

Author's purpose: The reason an author wrote a passage, such as to entertain, inform, or persuade.

Entertain: To write something fun or exciting for enjoyment.

Inform: To write something that teaches true facts.

Persuade: To write something that tries to change what a reader thinks or does.

Read a short paragraph and try to state the main idea in one sentence before you look at any answer choices. Then go back through the passage and underline every sentence that supports that main idea.

Next, decide the author's purpose. Ask if the passage made you feel entertained, taught you facts, or tried to convince you of something. Once you feel confident with these short passages, you can move on to Interpreting Texts for Meaning, or build more practice with Reading Comprehension Strategies.

Related lessons

• Reading for Meaning