PCParagraph Comprehension

Main Idea

The main idea is what the whole passage is about — not just one sentence, not a supporting detail, but the central point the author is making.

Formula Reference

  • Main idea = topic + what the author says about that topic
  • It usually appears in the first or last sentence of a paragraph — but not always
  • Ask: 'What would I title this passage?' — that answer is close to the main idea
  • Eliminate: too broad (covers more than the passage), too narrow (only covers one detail)
  • The main idea must be supported by every paragraph, not just one

What the ASVAB Paragraph Comprehension section tests

Paragraph Comprehension (PC) has 11 questions on the CAT-ASVAB. You read short passages — usually 4–8 sentences — and answer questions about them. Main idea questions are the most common type.

The challenge isn't reading speed. It's precision: knowing the difference between the main idea and a supporting detail.

What "main idea" means

The main idea is what the entire passage is arguing, describing, or explaining. Every sentence in the passage should connect to it. If a sentence doesn't connect, it's probably a detail.

Here's a useful test: if you removed the "main idea" answer choice from the passage, would the passage fall apart? It should. That's how you know it's the controlling idea.

Sample passage

Every branch of the military has its own physical fitness standards, but all share a common goal: ensuring service members can perform under physical stress. The Army emphasizes endurance with two-mile run requirements. The Navy focuses on swim readiness. The Marines set some of the most demanding standards across all categories. Despite these differences, the purpose behind every test is the same — operational readiness.

Main idea: Military fitness standards vary by branch but exist for one shared purpose — operational readiness.

Notice what that answer does: it acknowledges the variation (detail), then explains why it matters (the controlling idea). Answers that only cover one branch would be too narrow. An answer like "fitness is important" would be too vague.

The two wrong answer traps

Too narrow — picks one supporting fact. "The Marines have demanding standards" is true but doesn't cover the whole passage.

Too broad — goes beyond what the passage says. "Military training is comprehensive" drags in ideas the passage never makes.

The right answer fits like a lid on the passage — snug, not loose, not forced.

Practice move

After reading a passage, cover the answer choices and write one sentence summarizing the passage in your own words. Then uncover the choices and match. You'll find the correct answer almost immediately.

Common Pitfalls

  • Choosing a supporting detail that sounds important — the main idea explains the whole passage, not one part
  • Picking the topic word alone ('wolves') instead of what the author says about it ('wolves are misunderstood predators')
  • Selecting an answer that's too broad — if the passage is about Army nutrition guidelines, the main idea isn't 'health is important'
  • Confusing the title topic with the author's point — the topic is a noun, the main idea is a complete thought

Worked Examples

Q1: "Military working dogs undergo months of intensive obedience and detection training before deployment. Each dog is paired with a single handler for the duration of service. This bond improves performance and reduces stress for both animal and handler." What is the main idea? (A) Dogs make good pets. (B) Military working dogs are trained and paired with dedicated handlers to maximize effectiveness. (C) Dogs undergo obedience training. (D) Military service is stressful.

Answer: A covers too little. C is only one detail. D isn't in the passage. B captures the whole passage: training + pairing + performance outcome. Answer: B

Q2: "Dehydration reduces cognitive function, impairs reaction time, and lowers endurance. Field manuals recommend drinking water before thirst sets in. Soldiers who wait until they feel thirsty are already at a 2% fluid deficit." The main idea of this passage is: (A) Thirst is a reliable hydration signal. (B) Soldiers should carry water at all times. (C) Staying hydrated before thirst hits is critical to performance. (D) Dehydration causes cognitive problems.

Answer: A contradicts the passage. B isn't stated. D is one detail. C unifies all three sentences — performance, proactive hydration, the deficit fact. Answer: C

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