What is a Main Idea?
Students who are going to take reading tests often ask the question: What is a main idea?
A main idea is a statement that sums up the general theme of the passage.
So, remember that by definition, a main idea is general, rather than specific.
A main idea should not be confused with supporting details that provide specific information from the passage.
Incorrect answers on the reading test will often show supporting details from the passage.
Students sometime find this confusing; supporting details appear to be correct answers because they provide information from the passage that is accurate.
However, supporting details are too specific to be used as a main idea.
Types of Main Idea Reading Passages
You might see four different types of main idea reading passages and questions.
The first question type will ask: Which of the following statements best expresses the main idea of the passage?
Alternatively, the question might simply ask: What is the main idea of this passage?
The second type of main idea question will ask you to find the best title for a reading comprehension passage.
The third type of main idea question will give you four or five statements and then ask: Which of these statements is least relevant to the main idea of the passage?
The fourth type of main idea question will provide four or five sentences from the passage. It will then ask the question: Which of these sentences best supports the main idea of the passage?
Examples of each of these types of main idea passages and questions are provided below.
So, try the main idea questions that follow and study the answers.
What is the Main Idea? − Finding the Main Idea
(1) Read the passage below and answer the question that follows.
Although not a widespread practice, people have enjoyed eating meals in peculiar places for centuries. Grimond de la Reyniere staged a meal in a Paris mortuary in 1820, where he placed a coffin behind the seat of each guest. In London in the same year, a group of builders regularly had lunch 365 feet above ground, inside a new cross that they were erecting above St. Paul’s Cathedral. Louis Sherry had his guests dine on horseback in a dining room of a fine New York City restaurant in 1903. And as recent as last year, a restaurant opened in Latvia which offers its guests the experience of sleeping in a prison cell and eating typical prison fare.
Which of the statements best expresses the main idea of the passage?
A. Dining in odd locations takes place in many countries around the world.
B. Even though it is not a very common occurrence, some people enjoy dining in strange venues.
C. Peculiar dining habits are shared by the French, English, Americans, and Latvians.
D. Grimond de la Reyniere staged an eccentric meal in a Paris mortuary in 1820.
E. Dining experiences have to be unusual in order to be remembered by the guest.
When answering main idea questions, pay special attention to the first and last sentences of the paragraph, since this is where the main idea is often stated.
In the above passage, the main idea is stated in the first sentence: Although not a widespread practice, people have enjoyed eating meals in peculiar places for centuries.
The best paraphrase of this main idea from the options provided is: Even though it is not a very common occurrence, some people enjoy dining in strange venues.
So, the correct answer is B.
Answer A is an over-generalization. Only four countries are mentioned in the passage, so we cannot say that the practice takes place in many countries around the world.
Answer C is also an over-generalization. Only four dining experiences have been mentioned, so we cannot conclude that everyone from the countries mentioned has strange dining habits.
Answer D is a supporting detail from the passage. It is too specific to be the main idea.
Answer E is not supported by the text. This idea is not even mentioned in the passage.
What is the Main Idea? − Finding a Title
(2) Read the following passage and then find the best title from the options provided below.
The term “plastics” includes a wide array of materials that are man-made from carbon and hydrogen. One of the advantages of using plastic as a packaging material is its durability, but the product’s durability has also become a problem as plastic cups, bags, and containers are a major source of litter. A possible solution to this problem is biodegradable plastic. Containing starches and chemicals that are easily attacked by light and bacteria, biodegradable plastic gradually breaks into small pieces and is absorbed by the soil. Yet, those who oppose the use of biodegradable plastic point out that it can be expensive to produce and does not encourage recycling.
What is the most appropriate title of the passage above?
A. Biogradable Plastic: The Pros and Cons
B. The Use of Plastic in the World Today
C. Biogradable Plastic and the Problem of Litter
D. The Chemical Composition of Biodegradable Plastic
E. How to Encourage Recycling of Plastics
Questions that ask you to find the most appropriate title for a passage are really another type of main idea question.
As with the previous passage, you need to find the answer that best sums up the key points from the passage in a general way.
Avoid answers that restate specific points from the passage.
You also need to avoid over-generalizations, which are answers that are far too broad in their scope.
Sentences 1 and 2 give background information about why biodegradable plastic is sometimes used. Sentences 3 and 4 describe the benefits of biodegradable plastic. Sentence 5 points out the shortcomings of biodegradable plastic.
Accordingly, the main idea of the passage is the benefits and shortcomings of biodegradable plastic.
So, the correct answer is A.
Answer B is incorrect because it is an over-generalization.
The problem of litter is mentioned only in sentence 2, so answer choice C is too specific.
The chemical composition of plastic is mentioned only in sentence 1, so answer choice D is also too specific.
Even though recycling is mentioned in the last sentence, how to encourage recycling is not mentioned. So, answer choice E is incorrect.
Statement Least Relevant to the Main Idea
(3) Read the following passage and then select the statement that is least relevant to the main idea from the options provided below.
The spinning blades of a helicopter not only lift it into the air; they are also a means of forward propulsion. To lift the aircraft, the blades are rotated at an angle that meets the air stream. The throttle can be opened up to provide additional engine power, if necessary. Once the helicopter is in the air, its flight is controlled by further modifying the pitch of the blades. If the engine fails for some reason, the blades can be kept in operation in order to guide the vessel safely to the ground.
Which of the following sentences is least relevant to the main idea of the passage?
A. They are also a means of forward propulsion.
B. To lift the aircraft, the blades are rotated at an angle that meets the air stream.
C. The throttle can be opened up to provide additional engine power, if necessary.
D. Once the helicopter is in the air, its flight is controlled by further modifying the pitch of the blades.
E. If the engine fails for some reason, the blades can be kept in operation in order to guide the vessel safely to the ground.
For these types of main idea questions, look to see what subject the sentences have in common.
All of the sentences are describing the function of the blades of the helicopter, except for the sentence provided in answer choice C, which talks about the throttle.
So, the correct answer is C.
Best Supporting Statement for the Main Idea
(4) Read the following passage and then select the sentence that best supports the main idea from the options provided below.
When scholars attempt to decipher an unknown language, they have two main methods. The first method is the bilingual approach, in which the unknown text is placed alongside a copy of the text in a known language. The second method is to focus on the use of proper names in a text. Scholars sometimes know the names of kings and other rulers in the unknown language. Therefore, the second method can be effective, even though those who carry out the investigation are not familiar with the majority of the words from the language. Accordingly, scholars usually attempt either the bilingual approach or the proper names approach when trying to unlock the secrets of an unknown language.
Which sentence best supports the main idea of the passage?
A. The first method is the bilingual approach, in which the unknown text is placed alongside a copy of the text in a known language.
B. The second method is to focus on the use of proper names in a text.
C. Scholars sometimes know the names of kings and other rulers in the unknown language.
D. Therefore, the second method can be effective, even though those who carry out the investigation are not familiar with the majority of the words from the language.
E. Accordingly, scholars should attempt either the bilingual approach or the proper names approach when trying to unlock the secrets of an unknown language.
As stated above, the main idea of a passage is often provided in the first sentence of the text.
This is the case here as the first sentence states: When scholars attempt to decipher an unknown language, they have two main methods.
Answer choice E is the only answer that mentions both of the deciphering methods.
The other sentences provide specific information from the passage.
So, the correct answer is E.
Main Idea of a Paragraph
Note that you may also be asked to find the main idea of a paragraph.
The reading strategy for this is the same as for the passages above.