Approximately 35% of the 56 questions on the Reading test focus on main ideas and the details that support them. The test asks about main ideas in several different ways.
For example:
In a short passage (about one paragraph), the main idea is often stated in the first sentence and then restated in different words in the last sentence. The sentences in the middle usually provide facts, details, and examples that support that main idea.
In longer passages, the main idea is often stated in the last sentence of the first paragraph, but it can also appear in the second paragraph.
The “topic” of a passage is not the same as its main idea. The topic is what the passage is mostly about. You’ll usually see it named and referred to more than any other word or phrase.
Writers often use synonyms and pronouns to refer to the main topic, especially when the topic is a complex, multi-word idea.
For example:
The Enlightenment was a European intellectual movement of the seventeenth and eighteenth centuries that emphasized reason and individualism rather than tradition. It is known as the “long century” because it covered a period of 130 years.
The topic, the Enlightenment, is named once in the first sentence and then referred to twice with the pronoun “it” in the second sentence.
Here’s a more difficult example from On the Origin of Species by Charles Darwin found at Project Gutenberg:
To what does “this greater variability” refer?
a. The vast diversity of cultivated species and subspecies
b. Domestic productions
c. Parent species of today’s species and subspecies
d. Variations within species and subspecies of older cultivated plants
e. Individuals within a species or subspecies
Answer: d. Variations within species and subspecies of older cultivated plants is correct because Darwin is saying that older varieties of plants and animals show more variation within each group than individuals in a natural state do. The main idea appears twice: in the first sentence and again in the last sentence. In the last sentence, Darwin uses the shorthand phrase this greater variability to refer back to the earlier idea: variations within species and subspecies of older cultivated plants. Repeating the idea signals that it’s central to the passage.
a. The vast diversity of cultivated species and subspecies is incorrect because it focuses on diversity across species, not variation within a species or variety.
b. Domestic productions is incorrect because the passage isn’t defining that term or making it the focus.
c. Parent species of today’s species and subspecies is incorrect because the passage doesn’t discuss parent species as the main point.
e. Individuals within a species or subspecies is incorrect because it leaves out the key idea: the differences (variations) among those individuals.
The main point of a passage is what the author wants to say about the topic. Writers usually aren’t trying to say, “Nothing new here.” Instead, they’re usually adding a new claim, explanation, or perspective. That “new thing” is the main point.
For example:
What is the main idea of the passage?
a. Vinegar is helpful in cooking.
b. Vinegar can be used as an air freshener.
c. Vinegar is a useful cleaning product as well as a popular condiment.
d. The cleaning aisle is the wrong place to look for vinegar.
e. Vinegar is a fermented product containing acetic acid.
Answer: c. Vinegar is a useful cleaning product as well as a popular condiment is correct because the passage explains that vinegar is both a food item and a cleaning agent.
a. Vinegar is helpful in cooking is incorrect because the passage spends most of its time on vinegar’s non-cooking uses.
b. Vinegar can be used as an air freshener is incorrect because that’s only one supporting detail.
d. The cleaning aisle is the wrong place to look for vinegar is incorrect because the store location is a minor detail used to wrap up the passage.
e. Vinegar is a fermented product containing acetic acid is wrong because the passage never discusses vinegar’s chemical composition.
Questions that ask for the main point often paraphrase (restate) the main idea in different words.
For example:
What is the main idea of the passage?
a. Americans are planting more red and purple-leafed trees than green.
b. Red and purple-leafed trees are more common than they used to be.
c. Most red and purple-leafed trees are slow growers.
d. Red and purple-leafed trees are increasingly used as accents in all-green landscapes.
e. Red and purple-leafed trees have a bottom layer of evergreen leaves.
Answer: d. Red and purple-leafed trees are increasingly used as accents in all-green landscapes is correct because it accurately restates the passage’s main idea: “Red and purple-leafed trees have become increasingly common in the United States, where they add variety to the otherwise green treescape.”
a. Americans are planting more red and purple-leafed trees than green is incorrect because the passage doesn’t compare the number of red trees to the number of green trees.
b. Red and purple-leafed trees are more common than they used to be is incorrect because it leaves out an important part of the idea: these trees are used as accents that add variety to mostly green landscapes.
c. Most red and purple-leafed trees are slow growers is incorrect because the passage gives examples of both slow-growing and fast-growing trees.
e. Red and purple-leafed trees have a bottom layer of evergreen leaves is incorrect because that detail applies only to the Red Robin.
Many nonfiction passages in science and the social sciences follow a predictable pattern:
In an old idea/new idea passage, the main idea usually won’t appear in the first sentence, because the passage starts by describing the old belief.
For example:
Here, the old idea is that wearing hats causes baldness. The new idea is that baldness is caused by genetics and can be influenced by hormones and age. The transition word “however” signals that the passage is about to shift from the old idea to the new one.
There are a number of phrases that can alert you to the “old idea/new idea” pattern in a passage.
Old ideas:
New ideas:
Whenever a passage begins with an old idea, look for the transition word and focus on what comes after it. The old idea is usually background, not the main point.
For example:
What is the main idea of the passage?
a. Wilhelm Conrad Roentgen’s discovery of X-rays revolutionized medicine.
b. Anesthesia helped doctors perform more surgeries.
c. Wilhelm Conrad Roentgen won the first Nobel prize in physics.
d. CT scans and MRIs are better than X-rays for seeing inside the human body.
e. X-rays made it easier for doctors to perform surgery on awake patients
Answer: a. Wilhelm Conrad Roentgen’s discovery of X-rays revolutionized medicine is correct because the passage focuses on how X-rays changed what doctors could detect and led to later imaging technologies. The opening sentences describe the old limitation; the main point appears after “however.”
b. Anesthesia helped doctors perform more surgeries is incorrect because the passage doesn’t claim that anesthesia increased the number of surgeries.
c. Wilhelm Conrad Roentgen won the first Nobel prize in physics is incorrect because that information isn’t mentioned.
d. CT scans and MRIs are better than X-rays for seeing inside the human body is incorrect because CT scans and MRIs are mentioned only as later developments, not as the main focus.
e. X-rays made it easier for doctors to perform surgery on awake patients is wrong because the passage doesn’t discuss operating on conscious patients.
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