Main Idea

Reading Comprehension


Teacher's Guide
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Almost everything that you read will have a subject, main idea and details. It may help to imagine these characteristics as big, medium and small.

Subject : It's big and broad. It's the general topic. Imagine it as an entire city.

Main idea : It's the author's main point, what she's trying to prove. Imagine it as a neighborhood within the big city.

Details : These explain or support the main idea. They're smaller and more specific. Imagine them as people living in the neighborhood, which is in the city.


The subject of a book is big and broad. Try asking yourself, "What is this book about?" and answering in one to three words. Here are some examples:

The Amazing Spider-Man is a comic book. The subject is a superhero named Spiderman.

Walt Whitman: Words for America is a biography on the poet Walt Whitman. The subject is Walt Whitman's life.

The main idea is more specific than the subject. It gives us a little more information. Try asking yourself, "What is the author saying?" or "What is the most important thing I walk away with?" Remember, the main idea is not your opinion; it's the author's. Here are some examples:

The Amazing Spider-Man
What it is : A comic book
Subject : A superhero named Spider-Man
Main idea : Spider-Man is a brave superhero who fights crime.

Walt Whitman: Words for America
What it is : A biography about the poet Walt Whitman
Subject : Walt Whitman's life
Main idea : Walt Whitman's poetry was inspired by his time in the military.

The details are the most specific of all. They support the main idea. They often include descriptions about places, people or things. Here are some examples:

The Amazing Spider-Man
What it is: A comic book
Subject: A superhero named Spider-Man
Main idea: Spider-Man is a brave superhero who fights crime.
Details: Spider-Man has superpowers, including “spider-sense” and “web-shooters,” which fling a sticky web from his wrists and allow him to stick to different surfaces.

Walt Whitman: Words for America
What it is: A biography about the poet Walt Whitman
Subject: Walt Whitman's life
Main idea: Walt Whitman's poetry was inspired by his time in the military.
Details: Walt Whitman was a nurse during the Civil War. He took care of soldiers from both sides, the Union and the Confederacy. These experiences inspired much of his poetry.

Another word you might hear when talking about main idea is “theme.” A theme is similar to a moral or lesson. Books that are strictly informative, like textbooks or encyclopedias, will probably not have a theme. Novels, poems and other texts often do have one. Some examples of themes include friendship, courage, coming of age, good versus evil, love, freedom and many others.

Here are some examples:

The Amazing Spider-Man
What it is : A comic book
Subject : A superhero named Spider-Man
Main idea : Spider-Man is a brave superhero who fights crime.
Details : Spider-Man has superpowers, including “spider-sense” and “web-shooters,” which fling a sticky web from his wrists and allow him to stick to different surfaces.
Theme : Good versus evil

Walt Whitman: Words for America
What it is : A biography about the poet Walt Whitman
Subject : Walt Whitman's life
Main idea : Walt Whitman's poetry was inspired by his time in the military.
Details : Walt Whitman was a nurse during the Civil War. He took care of soldiers from both sides, the Union and the Confederacy. These experiences inspired much of his poetry.
Theme : Life & Death

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