ISAT Reading Comprehension: Main Idea 5 — Questions and Answers
Question 1: A scientific passage describes how deforestation increases carbon emissions, reduces biodiversity, and disrupts water cycles. The passage's main idea is:
- Deforestation causes widespread and interconnected environmental harm. (Correct answer)
- Carbon emissions are the most urgent environmental problem.
- Water cycles are poorly understood by scientists.
- Biodiversity loss is irreversible under all circumstances.
Correct answer: Deforestation causes widespread and interconnected environmental harm.
The three effects are all forms of environmental harm, so the main idea synthesizes them into a broad claim about deforestation's wide impact.
Question 2: An ISAT passage about digital privacy opens with a startling statistic about data breaches. The statistic is best classified as:
- A hook or supporting detail that introduces the main idea (Correct answer)
- The main idea itself
- The author's thesis counterargument
- An irrelevant fact included for interest
Correct answer: A hook or supporting detail that introduces the main idea
Opening statistics are typically used as attention-grabbing hooks that support the main idea rather than stating it directly.
Question 3: A passage argues: 'Space exploration, though costly, yields technological innovations, scientific discoveries, and international cooperation that benefit all of humanity.' A student summarizes this as 'Space is expensive.' What is wrong with this summary?
- It captures only the concession, not the main argument about benefits. (Correct answer)
- It is factually incorrect about the cost of space exploration.
- It uses informal language not found in the passage.
- Nothing is wrong; cost is the central topic.
Correct answer: It captures only the concession, not the main argument about benefits.
The author concedes cost but argues benefits outweigh it; a summary focusing only on cost reverses the passage's actual stance.
Question 4: Two answer choices for a main idea question are: (A) 'Antibiotics have saved millions of lives.' (B) 'Antibiotic overuse is creating dangerous drug-resistant bacteria that threaten global health.' A passage discusses the history of antibiotic success and the growing crisis of resistance. Which answer is better?
- B, because it reflects the passage's focus on the emerging crisis (Correct answer)
- A, because the history of success is mentioned first
- Neither, because the passage covers two unrelated topics
- Both equally, because the passage covers both subjects
Correct answer: B, because it reflects the passage's focus on the emerging crisis
When a passage moves from background to a central problem, the problem is typically the main idea the historical context sets up.
Question 5: A passage has five paragraphs. The main idea is stated in paragraph three and supported by paragraphs one, two, four, and five. This structure is called:
- A delayed or embedded thesis structure (Correct answer)
- An invalid passage structure for standardized tests
- An argumentative reversal
- A compare-and-contrast format
Correct answer: A delayed or embedded thesis structure
Authors sometimes place the thesis in the middle of a passage, using surrounding paragraphs to build toward and away from the central claim.
Question 6: A passage compares in-person and online learning across five criteria: cost, flexibility, social interaction, academic outcomes, and access. The main idea is most likely:
- In-person and online learning each offer distinct advantages depending on student needs. (Correct answer)
- Online learning is superior to in-person learning in every way.
- Social interaction is the most important factor in education.
- Cost is the primary driver of students' learning format choices.
Correct answer: In-person and online learning each offer distinct advantages depending on student needs.
A balanced comparison across multiple criteria suggests the main idea acknowledges trade-offs rather than declaring one format universally superior.
Question 7: A reader is unsure whether the main idea of a passage is stated explicitly or implied. Which approach best resolves this uncertainty?
- Identify the claim that best explains why the author wrote each paragraph, whether or not it appears word-for-word. (Correct answer)
- Assume the main idea is always in the first sentence.
- Select the most dramatic or surprising statement in the passage.
- Count which topic appears most often and name it the main idea.
Correct answer: Identify the claim that best explains why the author wrote each paragraph, whether or not it appears word-for-word.
Whether stated or implied, the main idea is the unifying claim that gives the author's reason for writing every part of the passage.
ISAT Reading Comprehension: Main Idea 5
A scientific passage describes how deforestation increases carbon emissions, reduces biodiversity, and disrupts water cycles.
The passage's main idea is: