Expository Writing: Ideas

Contributor: Delaine Thomas. Lesson ID: 12319

Has your mom or dad ever said to you, "What's the big idea?" when you were in trouble? Could you explain yourself? The "big idea" is important in your writing so learn to support what you write about!



English / Language Arts
learning style
personality style
Grade Level
Intermediate (3-5)
Lesson Type
Skill Sharpener

Lesson Plan - Get It!


Can you guess from this picture what you will be learning about in this lesson? What would happen if you removed the pillars? What does this have to do with your writing?

Expository writing is writing that is used to inform your audience about a topic.

It is also used to explain how something works or how something is done.

If you missed or care to review the previous Related Lesson in the Expository Writing series, please go to the right-hand sidebar.

It is very important when writing to have a strong main idea and supporting details. Take a look at the picture above. You may not think that it has much to do with writing, but study the structure carefully. The columns of the Parthenon support the roof of the building and keep it from falling down. The same rules of architecture apply to writing: your supporting details are like the columns that hold up, or support, your main idea, which is the roof.

If your supporting details do not relate to your main idea by further explaining it or by giving more information about it, your main idea will not have an impact on your reader.

Take out a piece of paper and pencil. As you watch the video below, write a definition, in your own words, for both "main idea" and "supporting details."

Main Idea | Award Winning Main Idea and Supporting Details Teaching Video | What is Main Idea?, from GrammarSongs by Melissa:


The video defined main idea as the big point or the most important idea that the writer is communicating to the reader. This is your topic sentence; this is where you inform your audience of what they are going to learn by reading your paper. Supporting details was defined in the video as those things that describe the main idea. Your supporting details should provide evidence or explain an element of your topic in greater detail.

You saw several examples of main ideas with supporting details in the video. However, look at one more for a little extra practice before continuing on to the Got It? section. Read the paragraph below:

There are lots of chores to do on a farm. Every morning, you must feed and water all the animals. The first thing we do is make bottles for the baby goats and calves and feed them first. Then, we put out fresh grain and water for them. The next thing we do is open the chicken coop and give the chickens grain and water. We also gather any eggs that were laid before we did our rounds. The cats and dog are the last ones to be fed but they don't seem to mind. Life on a farm is certainly busy!

What is the main idea of this paragraph? Did you say, "There are lots of chores to do on a farm"? If you did, you are right!

Do the other sentences support the main idea by telling more about it?

Yes, they do. They list the individual chores that are completed on the farm. In this example, the supporting details hold up the main idea (roof) well.

You will now identify the main idea yourself and check to see if the supporting details give more information about the main idea.

Continue to the Got It? section to practice finding more main ideas.

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