Identifying Main Ideas

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Identifying Main Ideas

If you want to be a good reader, you must be able to identify main ideas and supporting details.

What’s the difference between the topic and the main idea?

The topic is what a paragraph is about. The main idea is the point the writer is making about the topic. If we look at the topic sentence of a paragraph then, we should have a basic understanding of the main idea.

For example:

Cells phones today come equipped with HD cameras.

CELL PHONES is the topic. COMES EQUIPPED WITH HD CAMERAS tells us what the writer will say about the topic, and gives us a basic understanding of the main idea. What the writer says about the topic is also called the controlling idea.

[Topic + Controlling Idea = Topic Sentence] = Main Idea

Let’s look at another example. Let’s say your friend texts you this message.

“If you’re not busy tonight, can we study together in the library? I need more time preparing for the test next week. Algebra is difficult this year.”

In this message, what’s the point your friend is trying to make?

  • Is his point about how difficult algebra is?
  • Is his point he needs more time preparing for the test?
  • Or is his point he wants to study together tonight?

His point is he wants to study together in the library tonight. After he makes this point, then he supports it with two reasons; the first reason is he needs more time, and his second reason is algebra is difficult.

Look at it this way, think of the topic sentence (or main idea) as an umbrella that covers all the other information that supports the point.

This graphic helps us picture the relationship between the topic sentence and the supporting details. It also gives us a clearer picture of the main idea.

Let’s look at another example. This is a quote about Jaime Escalante taken from

“Escalante’s classroom challenges and successes were the topic of much public discussion in 1988. That year his story was the subject of a book entitled Jaime Escalante: The Best Teacher in America and a film called Stand and Deliver starring James Edward Olmos. Both educators and students have found Escalante’s work at Garfield inspiring.”

In this paragraph, what is the main idea? What point is the writer making?

  1. Escalante’s classroom became a much-discussed subject.
  2. A book was written about Escalante.
  3. A film was produced about his experiences.
  4. Students and educators were inspired by what he did.

Which one is a general statement, or which one is the topic sentence? If we look carefully, we’ll see B, C, & D give examples of his classroom becoming “a much discussed subject.

So we can say, A. Escalante’s classroom became a much-discussed subject, is our general statement, or topic sentence.

Richard Carrigan

Richard Carrigan has been an educator for over 30 years and a filmmaker for the past thirteen years. He has experience teaching business English and conversational English in Asia and teaching academic English at the university level in the United States. 

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