Main Idea and Supporting Details Study Guide

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Updated on Sep 29, 2011

Main Idea and Supporting Details

In this lesson, you'll discover that an author communicates one big idea and gives details about it.

THE MAIN IDEA is what a selection's mostly about—the most important thing the author wants readers to know. Other facts in the selection are details that support, or tell more about, the main idea. Sometimes the main idea is stated directly.

    Example 1

    Grass is one of Earth's most useful plants. Most people think of it as the stuff that grows in the yard and needs to be mowed, but there are thousands of different kinds. Wheat, rice, and other grains are grasses that help people and animals exist!

The main idea is stated: Grass is a useful plant. But sometimes you have to find the main idea yourself. To do that, use information from the text to figure it out.

    Example 2

    In 1483, Italian artist Leonardo da Vinci sketched a flying machine. He was also a scientist and fascinated by movement. His sketch showed a screw-like wing made of stiff linen. He never got it off the ground, but a real helicopter like it flew almost 500 years later!

The main idea is that Leonardo da Vinci designed the first helicopter more than 500 years ago. That's what the author most wants you to remember.

In the first example, supporting details are that wheat, rice, and other grains are useful grasses, and people and animals need grasses. In the second example, details are the year he drew the design, that it was a flying machine, what it looked like, and when the first real helicopter flew. Each detail supports or expands on the main idea.

In longer selections, each chapter or section may have its own main idea, but there's just one central idea for the whole selection. Sometimes the title can help you figure out the main idea. And you may find that some details add interest but aren't necessary to finding the main idea, like the fact that da Vinci was fascinated by movement, so they are not "supporting" details.

Practice exercises for this study guide can be found at:

Main Idea and Supporting Details Practice Exercises

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