Identifying Topics, Main Ideas, and Supporting Details

Understanding the topic, the gist, or the larger conceptual framework of a textbook chapter, an article, a paragraph, a sentence or a passage is a sophisticated reading task.  Being able to draw conclusions, evaluate, and critically interpret articles or chapters is important for overall comprehension in college reading.  Textbook chapters, articles, paragraphs, sentences, or passages all have topics and main ideas.  The topic is the broad, general theme or message.  It is what some call the subject.  The main idea is the "key concept" being expressed.  Details, major and minor, support the main idea by telling how, what, when, where, why, how much, or how many.  Locating the topic, main idea, and supporting details helps you understand the point(s) the writer is attempting to express.  Identifying the relationship between these will increase your comprehension.

The successful communication of any author's topic is only as good as the organization the author uses to build and define his/her subject matter.

Grasping the Main Idea:

A paragraph is a group of sentences related to a particular topic, or central theme.  Every paragraph has a key concept or main idea.  The main idea is the most important piece of information the author wants you to know about the concept of that paragraph.

When authors write they have an idea in mind that they are trying to get across.  This is especially true as authors compose paragraphs.  An author organizes each paragraph's main idea and supporting details in support of the topic or central theme, and each paragraph supports the paragraph preceding it.

A writer will state his/her main idea explicitly somewhere in the paragraph.  That main idea may be stated at the beginning of the paragraph, in the middle, or at the end.  The sentence in which the main idea is stated is the topic sentence of that paragraph.

The topic sentence announces the general theme ( or portion of the theme) to be dealt with in the paragraph.  Although the topic sentence may appear anywhere in the paragraph, it is usually first – and for a very good reason.  This sentence provides the focus for the writer while writing and for the reader while reading.  When you find the topic sentence, be sure to underline it so that it will stand out not only now, but also later when you review.

Identifying the Topic:

The first thing you must be able to do to get at the main idea of a paragraph is to identify the topic – the subject of the paragraph.  Think of the paragraph as a wheel with the topic being the hub – the central core around which the whole wheel (or paragraph) spins.  Your strategy for topic identification is simply to ask yourself the question, "What is this about?"  Keep asking yourself that question as you read a paragraph, until the answer to your question becomes clear.  Sometimes you can spot the topic by looking for a word or two that repeat.  Usually you can state the topic in a few words.

Let us try this topic-finding strategy.  Reread the first paragraph under the heading Grasping the Main Idea.  Ask yourself the question, "What is this paragraph about?"  To answer, say to yourself in your mind, "The author keeps talking about paragraphs and the way they are designed.  This must be the topic – paragraph organization."  Reread the second paragraph of the same section.  Ask yourself, "What is this paragraph about?"  Did you say to yourself, "This paragraph is about different ways to organize a paragraph"?  That is the topic.  Next, reread the third paragraph and see if you can find the topic of the paragraph.  How?  Write the topic in the margin next to this paragraph.  Remember, getting the main idea of a paragraph is crucial to reading.

The bulk of an expository paragraph is made up of supporting sentences (major and minor details), which help to explain or prove the main idea.  These sentences present facts, reasons, examples, definitions, comparison, contrasts, and other pertinent details.  They are most important because they sell the main idea.

The last sentence of a paragraph is likely to be a concluding sentence. It is used to sum up a discussion, to emphasize a point, or to restate all or part of the topic sentence so as to bring the paragraph to a close.  The last sentence may also be a transitional sentence leading to the next paragraph.

Of course, the paragraphs you'll be reading will be part of some longer piece of writing – a textbook chapter, a section of a chapter, or a newspaper or magazine article.  Besides expository paragraphs, in which new information is presented and discussed, these longer writings contain three types of paragraphs: introductory, transitional, and summarizing.

Introductory paragraphs tell you, in advance, such things as (1) the main ideas of the chapter or section; (2) the extent or limits of the coverage; (3) how the topic is developed; and (4) the writer's attitude toward the topic.  Transitional paragraphs are usually short; their sole function is to tie together what you have read so far and what is to come – to set the stage for succeeding ideas of the chapter or section.  Summarizing paragraphs are used to restate briefly the main ideas of the chapter or section.  The writer may also draw some conclusion from these ideas, or speculate on some conclusion based on the evidence he/she has presented.

All three types should alert you: the introductory paragraph of things to come; the transitional paragraph of a new topic; and the summarizing paragraph of main ideas that you should have gotten.


Read the following paragraph and underline the stated main idea.  Write down in your own words what you are able to conclude from the information.

The rules of conduct during an examination are clear.  No books, calculators or papers are allowed in the test room.  Proctors will not allow anyone with such items to take the test.  Anyone caught cheating will be asked to leave the room.  His or her test sheet will be taken.  The incident will be reported to the proper authority.  At the end of the test period, all materials will be returned to the proctor.  Failure to abide by these rules will result in a failing grade for this test.


You should have underlined the first sentence in the paragraph – this is the stated main idea.  What can be concluded from the information is: If you do not follow the rules, you will automatically fail the test.  This concluding information is found in the last sentence.

You can't comprehend the subject matter if you haven't identified
the topic, the main idea, and the supporting details.