Determine the main idea of a passage
Key Notes :
🔹 What is the Main Idea?
- The main idea is the central point or the most important message the author wants to communicate in a passage.
- It tells what the text is mostly about.
🔹 How to Identify the Main Idea
- Read the Passage Carefully
- Focus on the introduction and conclusion—these often contain the main idea.
- Look for repeated ideas or words.
- Ask Yourself
- What is the topic?
- What is the author saying about the topic?
- Look for Supporting Details
- These explain, prove, or give more information about the main idea.
- If a sentence doesn’t support the main idea, it may be irrelevant.
🔹 Where is the Main Idea Found?
- Beginning: Often the first sentence (topic sentence).
- Middle: Sometimes it’s in the middle of the paragraph.
- End: Occasionally the last sentence summarizes the idea.
- Implied: Not directly stated; you must infer it from the passage.
🔹 Tips for Finding the Main Idea
- Underline or highlight important ideas.
- Summarize each paragraph in your own words.
- Ignore small details and focus on what the author is trying to show overall.
- Use a graphic organizer (like a main idea tree or concept map).
🔹 Examples
Passage Example:
“Rainforests are important for the environment. They produce oxygen, provide habitat for animals, and help regulate climate. However, many rainforests are being cut down for wood and farmland.”
Main Idea:
Rainforests are vital to the environment but are being destroyed.
Learn with an example
👉 Read the passage.
Maggots as Medicine
While serving in World War I, surgeon William Baer noticed something curious: soldiers whose wounds were infested with maggots (the wormlike immature larval form of flies) recovered faster than those whose wounds were maggot-free. Although Baer was not the first military doctor to take note of this phenomenon, he was the first to apply his observations to the problem of non-healing wounds. In the 1920s, he began treating hospital patients’ serious wounds with maggots. The maggots consumed dead tissue, effectively cleaning the wounds and helping the patients heal. While maggot therapy fell out of favour after bacteria-killing antibiotic medications were introduced, it has made a comeback in modern medicine. Many clinicians have found that the treatment can be effective for certain types of severe wounds that do not respond to antibiotics.
What is the main idea of the passage?
- William Baer, a military surgeon, observed the advantages of maggot-infested wounds while serving in World War I.
- As noted by William Baer, some severe wounds can be effectively treated with maggots, which consume dead tissue.
The main idea of the passage is As noted by William Baer, some severe wounds can be effectively treated with maggots, which consume dead tissue.
Notice the phrases apply his observations to the problem and effectively. They suggest that the main idea involves a possible solution to a problem. Here, the main idea is that Baer’s maggot therapy can be used to treat non-healing wounds.
👉 Read the passage.
Synaesthesia: Mixed-Up Senses
We generally think of our senses as having completely separate functions. This is a logical assumption; after all, we can’t see with our ears or taste with our eyes. For people with a condition called synaesthesia, however, senses can be conflated, or mixed together. In fact, the word synaesthesia, derived from Greek, literally means ‘sensations together’. This combining of senses causes interesting sensory experiences. For example, some synaesthetes (people who experience synaesthesia) imagine tasting a particular flavour whenever they hear a certain sound. Others ‘hear’ a sound in their minds whenever they touch a certain object. The most common types of synaesthesia involve colours. In one common subtype, for instance, synaesthetes associate different colours with different letters of the alphabet. Typically, synaesthetes are not bothered by their synaesthesia; in fact, many enjoy it.
What is the main idea of the passage?
- People with synaesthesia may hear a sound when they touch an object.
- People with synaesthesia experience a fusing of different senses.
The main idea of the passage is People with synaesthesia experience a fusing of different senses.
The title suggests that the main idea involves the mixing of senses. In addition, many of the details describe various sensory combinations that may occur. The title and details together suggest the main idea is that synaesthesia causes a combining of sensory experiences.
👉 Read the passage.
Overlooked Women in Science
Historically, men have dominated the field of science, and many women have not received professional credit or public recognition for their work. Rosalind Franklin, for example, was a chemist who did groundbreaking research into the structure of DNA, a type of molecule in cells that helps control their growth, activity and reproduction. Franklin’s X-ray photograph of DNA was shared, without her knowledge, with biologist James Watson. Franklin’s work helped Watson and fellow researcher Francis Crick discover the structure of DNA, but she received no credit when they won a Nobel Prize for their model of DNA in 1962. Another scientist denied credit for her work was Jocelyn Bell Burnell. Bell Burnell was a postgraduate student in 1967 when she discovered the first radio pulsars—small, dense rotating stars that emit radio waves. However, the credit was given to her supervisor, Antony Hewish, who received a Nobel Prize in 1974.
What is the main idea of the passage?
- Jocelyn Bell Burnell failed to receive credit for her 1967 discovery of radio pulsars.
- Women have often failed to receive the credit they deserve for their scientific work.
The main idea of the passage is Women have often failed to receive the credit they deserve for their scientific work.
The details include two examples of female scientists who did not receive recognition in their time. These details suggest that the main idea involves women not receiving credit for their work. The word overlooked in the title also suggests this idea.
let’s practice!
Read the passage.
Sign Language on Martha’s Vineyard
While researching Martha’s Vineyard, an island off the coast of the north-eastern United States, anthropologist Nora Groce made a remarkable discovery. She learned that from the 1600s until the early 1900s, almost all the residents of two towns on the island—West Tisbury and Chilmark—were fluent in sign language. During these years, the towns had an unusually high population of deaf people, due to a form of hereditary deafness that ran in many Martha’s Vineyard families. Consequently, a bilingual society developed. The islanders didn’t attend special sign language classes; they simply learned the language as they grew up. One of the most interesting aspects of the phenomenon was that, in the absence of language barriers, deafness was not perceived as a disability. As one Vineyarder explained to Groce, deaf people were seen as ‘just like everyone else’.