Understanding Nonfiction Texts

Nonfiction books tell you true facts about real things, like sharks, volcanoes, or the solar system. In this lesson, you will learn how to find the main idea of a nonfiction passage, spot the key details that support it, and use text features to understand the facts even faster.

The main idea is the one big point a nonfiction passage is mostly about. Every other sentence in the passage helps explain that one big point.

Imagine you read a page about sharks. It might say sharks have gills, sharks swim fast, and sharks have sharp teeth. All of these sentences are about one big idea: sharks are built for hunting in the ocean. That big idea is the main idea.

To find the main idea, ask yourself, "What is most of this page really about?" Do not just repeat the first sentence. Think about what all the sentences have in common.

Key details are the small facts that support the main idea. They give proof and examples that explain why the main idea is true.

In the shark passage, the key details are the facts that back up the main idea. "Sharks have gills" is a key detail. "Sharks swim fast" is another key detail. "Sharks have sharp teeth" is a third key detail.

The picture below shows how one main idea connects to several key details, just like in the shark example.

Nonfiction books use special parts called text features to help you find facts quickly. Here are text features you will see often.

• Headings: Short titles above a section that tell you what that part is about.
• Bold words: Dark, heavy words that point out an important term.
• Captions: Small sentences under a photo that explain what the photo shows.
• Diagrams and labels: Pictures with words pointing to parts, like the parts of a shark's body.

Before you read the whole page, look at the heading first. Then look at any photos and read their captions. This gives you a quick idea of what facts are coming, before you even read the full sentences.

A summary is a short retelling of a passage in your own words. A good summary has two parts: the main idea, and two or three key details.

Here is a summary of the shark passage: "Sharks are built for hunting. They have gills to breathe underwater, they swim fast, and they have sharp teeth." Notice this summary is much shorter than the full passage, but it still tells the most important facts.

When you write your own summary, do not list every single fact. Pick the main idea and only the details that matter most.

Main Idea: The one big point that a nonfiction passage is mostly about.

Key Detail: A small fact that supports and explains the main idea.

Text Feature: A special part of a nonfiction book, like a heading, caption, or bold word, that helps you find facts.

Caption: A short sentence under a photo that tells you what the photo shows.

Summary: A short retelling of a passage that gives the main idea and the most important details.

Pick a nonfiction book about an animal or a place. Read the heading first, then look at the photos and captions. Write down the main idea in one sentence, then list two or three key details that support it. Finally, try saying your summary out loud in three sentences or fewer.

Related lessons

• Reading Informational Texts